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transformers 0.5.0.0 → 0.6.3.0

raw patch · 35 files changed

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Control/Applicative/Backwards.hs view
@@ -1,11 +1,12 @@ {-# LANGUAGE CPP #-} #if __GLASGOW_HASKELL__ >= 702 {-# LANGUAGE Safe #-}+{-# LANGUAGE DeriveGeneric #-} #endif-#if __GLASGOW_HASKELL__ >= 704+#if __GLASGOW_HASKELL__ >= 706 {-# LANGUAGE PolyKinds #-} #endif-#if __GLASGOW_HASKELL__ >= 710+#if __GLASGOW_HASKELL__ >= 710 && __GLASGOW_HASKELL__ < 802 {-# LANGUAGE AutoDeriveTypeable #-} #endif -----------------------------------------------------------------------------@@ -26,22 +27,40 @@     Backwards(..),   ) where +#if MIN_VERSION_base(4,18,0)+import Data.Foldable1 (Foldable1(foldMap1))+#endif import Data.Functor.Classes+#if MIN_VERSION_base(4,12,0)+import Data.Functor.Contravariant+#endif+#if __GLASGOW_HASKELL__ >= 704+import GHC.Generics+#endif -import Prelude hiding (foldr, foldr1, foldl, foldl1)+import Prelude hiding (foldr, foldr1, foldl, foldl1, null, length) import Control.Applicative import Data.Foldable-import Data.Traversable+#if !(MIN_VERSION_base(4,8,0)) || defined(__MHS__)+import Data.Traversable (Traversable(traverse, sequenceA))+#endif  -- | The same functor, but with an 'Applicative' instance that performs -- actions in the reverse order. newtype Backwards f a = Backwards { forwards :: f a }+#if __GLASGOW_HASKELL__ >= 710+    deriving (Generic, Generic1)+#elif __GLASGOW_HASKELL__ >= 704+    deriving (Generic)+#endif  instance (Eq1 f) => Eq1 (Backwards f) where     liftEq eq (Backwards x) (Backwards y) = liftEq eq x y+    {-# INLINE liftEq #-}  instance (Ord1 f) => Ord1 (Backwards f) where     liftCompare comp (Backwards x) (Backwards y) = liftCompare comp x y+    {-# INLINE liftCompare #-}  instance (Read1 f) => Read1 (Backwards f) where     liftReadsPrec rp rl = readsData $@@ -59,26 +78,68 @@ -- | Derived instance. instance (Functor f) => Functor (Backwards f) where     fmap f (Backwards a) = Backwards (fmap f a)+    {-# INLINE fmap #-}+    x <$ Backwards a = Backwards (x <$ a)+    {-# INLINE (<$) #-}  -- | Apply @f@-actions in the reverse order. instance (Applicative f) => Applicative (Backwards f) where     pure a = Backwards (pure a)+    {-# INLINE pure #-}     Backwards f <*> Backwards a = Backwards (a <**> f)+    {-# INLINE (<*>) #-}+#if MIN_VERSION_base(4,10,0)+    liftA2 f (Backwards m) (Backwards n) = Backwards $ liftA2 (flip f) n m+    {-# INLINE liftA2 #-}+#endif+#if MIN_VERSION_base(4,2,0)+    Backwards xs *> Backwards ys = Backwards (ys <* xs)+    {-# INLINE (*>) #-}+    Backwards ys <* Backwards xs = Backwards (xs *> ys)+    {-# INLINE (<*) #-}+#endif  -- | Try alternatives in the same order as @f@. instance (Alternative f) => Alternative (Backwards f) where     empty = Backwards empty+    {-# INLINE empty #-}     Backwards x <|> Backwards y = Backwards (x <|> y)+    {-# INLINE (<|>) #-}  -- | Derived instance. instance (Foldable f) => Foldable (Backwards f) where     foldMap f (Backwards t) = foldMap f t+    {-# INLINE foldMap #-}     foldr f z (Backwards t) = foldr f z t+    {-# INLINE foldr #-}     foldl f z (Backwards t) = foldl f z t+    {-# INLINE foldl #-}     foldr1 f (Backwards t) = foldr1 f t+    {-# INLINE foldr1 #-}     foldl1 f (Backwards t) = foldl1 f t+    {-# INLINE foldl1 #-}+#if MIN_VERSION_base(4,8,0)+    null (Backwards t) = null t+    length (Backwards t) = length t+#endif +#if MIN_VERSION_base(4,18,0) -- | Derived instance.+instance (Foldable1 f) => Foldable1 (Backwards f) where+    foldMap1 f (Backwards t) = foldMap1 f t+    {-# INLINE foldMap1 #-}+#endif++-- | Derived instance. instance (Traversable f) => Traversable (Backwards f) where     traverse f (Backwards t) = fmap Backwards (traverse f t)+    {-# INLINE traverse #-}     sequenceA (Backwards t) = fmap Backwards (sequenceA t)+    {-# INLINE sequenceA #-}++#if MIN_VERSION_base(4,12,0)+-- | Derived instance.+instance (Contravariant f) => Contravariant (Backwards f) where+    contramap f = Backwards . contramap f . forwards+    {-# INLINE contramap #-}+#endif
Control/Applicative/Lift.hs view
@@ -1,8 +1,9 @@ {-# LANGUAGE CPP #-} #if __GLASGOW_HASKELL__ >= 702 {-# LANGUAGE Safe #-}+{-# LANGUAGE DeriveGeneric #-} #endif-#if __GLASGOW_HASKELL__ >= 710+#if __GLASGOW_HASKELL__ >= 710 && __GLASGOW_HASKELL__ < 802 {-# LANGUAGE AutoDeriveTypeable #-} #endif -----------------------------------------------------------------------------@@ -23,35 +24,52 @@     Lift(..),     unLift,     mapLift,+    elimLift,     -- * Collecting errors     Errors,     runErrors,-    failure+    failure,+    eitherToErrors   ) where +#if MIN_VERSION_base(4,18,0)+import Data.Foldable1 (Foldable1(foldMap1))+#endif import Data.Functor.Classes  import Control.Applicative-import Data.Foldable (Foldable(foldMap)) import Data.Functor.Constant+#if !(MIN_VERSION_base(4,8,0)) || defined(__MHS__)+import Data.Foldable (Foldable(foldMap)) import Data.Monoid (Monoid(..)) import Data.Traversable (Traversable(traverse))+#endif+#if __GLASGOW_HASKELL__ >= 704+import GHC.Generics+#endif  -- | Applicative functor formed by adding pure computations to a given -- applicative functor. data Lift f a = Pure a | Other (f a)+#if __GLASGOW_HASKELL__ >= 710+    deriving (Generic, Generic1)+#elif __GLASGOW_HASKELL__ >= 704+    deriving (Generic)+#endif  instance (Eq1 f) => Eq1 (Lift f) where     liftEq eq (Pure x1) (Pure x2) = eq x1 x2     liftEq _ (Pure _) (Other _) = False     liftEq _ (Other _) (Pure _) = False     liftEq eq (Other y1) (Other y2) = liftEq eq y1 y2+    {-# INLINE liftEq #-}  instance (Ord1 f) => Ord1 (Lift f) where     liftCompare comp (Pure x1) (Pure x2) = comp x1 x2     liftCompare _ (Pure _) (Other _) = LT     liftCompare _ (Other _) (Pure _) = GT     liftCompare comp (Other y1) (Other y2) = liftCompare comp y1 y2+    {-# INLINE liftCompare #-}  instance (Read1 f) => Read1 (Lift f) where     liftReadsPrec rp rl = readsData $@@ -71,44 +89,70 @@ instance (Functor f) => Functor (Lift f) where     fmap f (Pure x) = Pure (f x)     fmap f (Other y) = Other (fmap f y)+    {-# INLINE fmap #-}  instance (Foldable f) => Foldable (Lift f) where     foldMap f (Pure x) = f x     foldMap f (Other y) = foldMap f y+    {-# INLINE foldMap #-}  instance (Traversable f) => Traversable (Lift f) where     traverse f (Pure x) = Pure <$> f x     traverse f (Other y) = Other <$> traverse f y+    {-# INLINE traverse #-}  -- | A combination is 'Pure' only if both parts are. instance (Applicative f) => Applicative (Lift f) where     pure = Pure-    Pure f <*> Pure x = Pure (f x)-    Pure f <*> Other y = Other (f <$> y)-    Other f <*> Pure x = Other (($ x) <$> f)-    Other f <*> Other y = Other (f <*> y)+    {-# INLINE pure #-}+    Pure f <*> ax = f <$> ax+    Other f <*> ax = Other (f <*> unLift ax)+    {-# INLINE (<*>) #-}  -- | A combination is 'Pure' only either part is. instance (Alternative f) => Alternative (Lift f) where     empty = Other empty+    {-# INLINE empty #-}     Pure x <|> _ = Pure x     Other _ <|> Pure y = Pure y     Other x <|> Other y = Other (x <|> y)+    {-# INLINE (<|>) #-} +#if MIN_VERSION_base(4,18,0)+instance (Foldable1 f) => Foldable1 (Lift f) where+    foldMap1 f (Pure x)  = f x+    foldMap1 f (Other y) = foldMap1 f y+    {-# INLINE foldMap1 #-}+#endif+ -- | Projection to the other functor. unLift :: (Applicative f) => Lift f a -> f a unLift (Pure x) = pure x unLift (Other e) = e+{-# INLINE unLift #-}  -- | Apply a transformation to the other computation. mapLift :: (f a -> g a) -> Lift f a -> Lift g a mapLift _ (Pure x) = Pure x mapLift f (Other e) = Other (f e)+{-# INLINE mapLift #-} +-- | Eliminator for 'Lift'.+--+-- * @'elimLift' f g . 'pure' = f@+--+-- * @'elimLift' f g . 'Other' = g@+--+elimLift :: (a -> r) -> (f a -> r) -> Lift f a -> r+elimLift f _ (Pure x) = f x+elimLift _ g (Other e) = g e+{-# INLINE elimLift #-}+ -- | An applicative functor that collects a monoid (e.g. lists) of errors. -- A sequence of computations fails if any of its components do, but--- unlike monads made with 'ExceptT' from "Control.Monad.Trans.Except",--- these computations continue after an error, collecting all the errors.+-- unlike monads made with 'Control.Monad.Trans.Except.ExceptT' from+-- "Control.Monad.Trans.Except", these computations continue after an+-- error, collecting all the errors. -- -- * @'pure' f '<*>' 'pure' x = 'pure' (f x)@ --@@ -129,7 +173,13 @@ runErrors :: Errors e a -> Either e a runErrors (Other (Constant e)) = Left e runErrors (Pure x) = Right x+{-# INLINE runErrors #-}  -- | Report an error. failure :: e -> Errors e a failure e = Other (Constant e)+{-# INLINE failure #-}++-- | Convert from 'Either' to 'Errors' (inverse of 'runErrors').+eitherToErrors :: Either e a -> Errors e a+eitherToErrors = either failure Pure
Control/Monad/Signatures.hs view
@@ -2,7 +2,7 @@ #if __GLASGOW_HASKELL__ >= 702 {-# LANGUAGE Safe #-} #endif-#if __GLASGOW_HASKELL__ >= 704+#if __GLASGOW_HASKELL__ >= 706 {-# LANGUAGE PolyKinds #-} #endif -----------------------------------------------------------------------------@@ -27,23 +27,27 @@ -- introduced in "Control.Monad.Trans.Cont". -- Any lifting function @liftCallCC@ should satisfy ----- * @'lift' (f k) = f' ('lift' . k) => 'lift' (cf f) = liftCallCC cf f'@+-- @'Control.Monad.Trans.Class.lift' (f k) = f' ('Control.Monad.Trans.Class.lift' . k) => 'Control.Monad.Trans.Class.lift' (cf f) = liftCallCC cf f'@ --+-- This implies that on entry to the continuation any outer monad+-- transformer effect inside @callCC@ will have been rolled back. type CallCC m a b = ((a -> m b) -> m a) -> m a  -- | Signature of the @catchE@ operation, -- introduced in "Control.Monad.Trans.Except". -- Any lifting function @liftCatch@ should satisfy ----- * @'lift' (cf m f) = liftCatch ('lift' . cf) ('lift' f)@+-- @'Control.Monad.Trans.Class.lift' (cf m h) = liftCatch cf ('Control.Monad.Trans.Class.lift' m) ('Control.Monad.Trans.Class.lift' . h)@ --+-- This implies that on entry to the handler function any outer monad+-- transformer effect inside @catchE@ will have been rolled back. type Catch e m a = m a -> (e -> m a) -> m a  -- | Signature of the @listen@ operation, -- introduced in "Control.Monad.Trans.Writer". -- Any lifting function @liftListen@ should satisfy ----- * @'lift' . liftListen = liftListen . 'lift'@+-- @'Control.Monad.Trans.Class.lift' . liftListen = liftListen . 'Control.Monad.Trans.Class.lift'@ -- type Listen w m a = m a -> m (a, w) @@ -51,6 +55,6 @@ -- introduced in "Control.Monad.Trans.Writer". -- Any lifting function @liftPass@ should satisfy ----- * @'lift' . liftPass = liftPass . 'lift'@+-- @'Control.Monad.Trans.Class.lift' . liftPass = liftPass . 'Control.Monad.Trans.Class.lift'@ -- type Pass w m a =  m (a, w -> w) -> m a
+ Control/Monad/Trans/Accum.hs view
@@ -0,0 +1,319 @@+{-# LANGUAGE CPP #-}+#if __GLASGOW_HASKELL__ >= 702+{-# LANGUAGE Safe #-}+{-# LANGUAGE DeriveGeneric #-}+#endif+#if __GLASGOW_HASKELL__ >= 710 && __GLASGOW_HASKELL__ < 802+{-# LANGUAGE AutoDeriveTypeable #-}+#endif+-----------------------------------------------------------------------------+-- |+-- Module      :  Control.Monad.Trans.Accum+-- Copyright   :  (c) Nickolay Kudasov 2016+-- License     :  BSD-style (see the file LICENSE)+--+-- Maintainer  :  R.Paterson@city.ac.uk+-- Stability   :  experimental+-- Portability :  portable+--+-- The lazy 'AccumT' monad transformer, which adds accumulation+-- capabilities (such as declarations or document patches) to a given monad.+-- Each computation has access to the combination of the input environment+-- and outputs added so far, and returns the outputs added.+--+-- In applications requiring only the ability to accumulate an output and+-- to inspect the output so far, it would be considerably more efficient+-- to use "Control.Monad.Trans.State" instead.+-----------------------------------------------------------------------------++module Control.Monad.Trans.Accum (+    -- * The Accum monad+    Accum,+    accum,+    runAccum,+    execAccum,+    evalAccum,+    mapAccum,+    -- * The AccumT monad transformer+    AccumT(..),+    execAccumT,+    evalAccumT,+    mapAccumT,+    -- * Accum operations+    look,+    looks,+    add,+    -- * Lifting other operations+    liftCallCC,+    liftCallCC',+    liftCatch,+    liftListen,+    liftPass,+    -- * Monad transformations+    readerToAccumT,+    writerToAccumT,+    accumToStateT,+  ) where++import Control.Monad.IO.Class+import Control.Monad.Trans.Class+import Control.Monad.Trans.Reader (ReaderT(..))+import Control.Monad.Trans.Writer (WriterT(..))+import Control.Monad.Trans.State  (StateT(..))+import Data.Functor.Identity++import Control.Applicative+import Control.Monad+#if MIN_VERSION_base(4,9,0)+import qualified Control.Monad.Fail as Fail+#endif+import Control.Monad.Fix+import Control.Monad.Signatures+#if !MIN_VERSION_base(4,8,0)+import Data.Monoid+#endif+#if __GLASGOW_HASKELL__ >= 704+import GHC.Generics+#endif++-- ---------------------------------------------------------------------------+-- | An accumulation monad (non-strict) parameterized by the type @w@+-- of output to accumulate.+--+-- This monad is a more complex extension of both the reader and writer+-- monads.  The 'return' function produces the output 'mempty', while @m+-- '>>=' k@ uses the output of @m@ both to extend the initial environment+-- of @k@ and to combine with the output of @k@:+--+-- <<images/bind-AccumT.svg>>+--+-- In applications requiring only the ability to accumulate an output and+-- to inspect the output so far, it would be considerably more efficient+-- to use a state monad.+type Accum w = AccumT w Identity++-- | Construct an accumulation computation from a (result, output) pair.+-- (The inverse of 'runAccum'.)+accum :: (Monad m) => (w -> (a, w)) -> AccumT w m a+accum f = AccumT $ \ w -> return (f w)+{-# INLINE accum #-}++-- | Unwrap an accumulation computation as a (result, output) pair.+-- (The inverse of 'accum'.)+runAccum :: Accum w a -> w -> (a, w)+runAccum m = runIdentity . runAccumT m+{-# INLINE runAccum #-}++-- | Extract the output from an accumulation computation.+--+-- * @'execAccum' m w = 'snd' ('runAccum' m w)@+execAccum :: Accum w a -> w -> w+execAccum m w = snd (runAccum m w)+{-# INLINE execAccum #-}++-- | Evaluate an accumulation computation with the given initial output history+-- and return the final value, discarding the final output.+--+-- * @'evalAccum' m w = 'fst' ('runAccum' m w)@+evalAccum :: (Monoid w) => Accum w a -> w -> a+evalAccum m w = fst (runAccum m w)+{-# INLINE evalAccum #-}++-- | Map both the return value and output of a computation using+-- the given function.+--+-- * @'runAccum' ('mapAccum' f m) = f . 'runAccum' m@+mapAccum :: ((a, w) -> (b, w)) -> Accum w a -> Accum w b+mapAccum f = mapAccumT (Identity . f . runIdentity)+{-# INLINE mapAccum #-}++-- ---------------------------------------------------------------------------+-- | An accumulation monad parameterized by:+--+--   * @w@ - the output to accumulate.+--+--   * @m@ - The inner monad.+--+-- This monad transformer is a more complex extension of both the reader+-- and writer monad transformers.  The 'return' function produces the+-- output 'mempty', while @m '>>=' k@ uses the output of @m@ both to+-- extend the initial environment of @k@ and to combine with the output+-- of @k@:+--+-- <<images/bind-AccumT.svg>>+--+-- In applications requiring only the ability to accumulate an output and+-- to inspect the output so far, it would be considerably more efficient+-- to use a state monad transformer.+--+-- @AccumT w m@ is strict if and only if @m@ is.+newtype AccumT w m a = AccumT {+    -- | Unwrap an accumulation computation.  For example, in the call+    --+    -- @    (value, locals) <- runAccumT action globals@+    --+    -- the action is fed an initial environment @globals@, and @locals@ is+    -- the sum of all arguments to calls of 'add' executed by the action.+    runAccumT :: w -> m (a, w)+    }+#if __GLASGOW_HASKELL__ >= 704+    deriving (Generic)+#endif++-- | Extract the output from an accumulation computation.+--+-- * @'execAccumT' m w = 'liftM' 'snd' ('runAccumT' m w)@+execAccumT :: (Monad m) => AccumT w m a -> w -> m w+execAccumT m w = do+    ~(_, w') <- runAccumT m w+    return w'+{-# INLINE execAccumT #-}++-- | Evaluate an accumulation computation with the given initial output+-- history and return the final value, discarding the final output.+--+-- * @'evalAccumT' m w = 'liftM' 'fst' ('runAccumT' m w)@+evalAccumT :: (Monad m, Monoid w) => AccumT w m a -> w -> m a+evalAccumT m w = do+    ~(a, _) <- runAccumT m w+    return a+{-# INLINE evalAccumT #-}++-- | Map both the return value and output of a computation using the+-- given function.+--+-- * @'runAccumT' ('mapAccumT' f m) = f . 'runAccumT' m@+mapAccumT :: (m (a, w) -> n (b, w)) -> AccumT w m a -> AccumT w n b+mapAccumT f m = AccumT (f . runAccumT m)+{-# INLINE mapAccumT #-}++instance (Functor m) => Functor (AccumT w m) where+    fmap f = mapAccumT $ fmap $ \ ~(a, w) -> (f a, w)+    {-# INLINE fmap #-}++instance (Monoid w, Functor m, Monad m) => Applicative (AccumT w m) where+    pure a  = AccumT $ const $ return (a, mempty)+    {-# INLINE pure #-}+    mf <*> mv = AccumT $ \ w -> do+      ~(f, w')  <- runAccumT mf w+      ~(v, w'') <- runAccumT mv (w `mappend` w')+      return (f v, w' `mappend` w'')+    {-# INLINE (<*>) #-}++instance (Monoid w, Functor m, MonadPlus m) => Alternative (AccumT w m) where+    empty   = AccumT $ const mzero+    {-# INLINE empty #-}+    m <|> n = AccumT $ \ w -> runAccumT m w `mplus` runAccumT n w+    {-# INLINE (<|>) #-}++instance (Monoid w, Functor m, Monad m) => Monad (AccumT w m) where+#if !(MIN_VERSION_base(4,8,0))+    return a  = AccumT $ const $ return (a, mempty)+    {-# INLINE return #-}+#endif+    m >>= k  = AccumT $ \ w -> do+        ~(a, w')  <- runAccumT m w+        ~(b, w'') <- runAccumT (k a) (w `mappend` w')+        return (b, w' `mappend` w'')+    {-# INLINE (>>=) #-}+#if !(MIN_VERSION_base(4,13,0))+    fail msg = AccumT $ const (fail msg)+    {-# INLINE fail #-}+#endif++#if MIN_VERSION_base(4,9,0)+instance (Monoid w, Fail.MonadFail m) => Fail.MonadFail (AccumT w m) where+    fail msg = AccumT $ const (Fail.fail msg)+    {-# INLINE fail #-}+#endif++instance (Monoid w, Functor m, MonadPlus m) => MonadPlus (AccumT w m) where+    mzero       = AccumT $ const mzero+    {-# INLINE mzero #-}+    m `mplus` n = AccumT $ \ w -> runAccumT m w `mplus` runAccumT n w+    {-# INLINE mplus #-}++instance (Monoid w, Functor m, MonadFix m) => MonadFix (AccumT w m) where+    mfix m = AccumT $ \ w -> mfix $ \ ~(a, _) -> runAccumT (m a) w+    {-# INLINE mfix #-}++instance (Monoid w) => MonadTrans (AccumT w) where+    lift m = AccumT $ const $ do+        a <- m+        return (a, mempty)+    {-# INLINE lift #-}++instance (Monoid w, Functor m, MonadIO m) => MonadIO (AccumT w m) where+    liftIO = lift . liftIO+    {-# INLINE liftIO #-}++-- | @'look'@ is an action that fetches all the previously accumulated output.+look :: (Monoid w, Monad m) => AccumT w m w+look = AccumT $ \ w -> return (w, mempty)++-- | @'look'@ is an action that retrieves a function of the previously accumulated output.+looks :: (Monoid w, Monad m) => (w -> a) -> AccumT w m a+looks f = AccumT $ \ w -> return (f w, mempty)++-- | @'add' w@ is an action that produces the output @w@.+add :: (Monad m) => w -> AccumT w m ()+add w = accum $ const ((), w)+{-# INLINE add #-}++-- | Uniform lifting of a @callCC@ operation to the new monad.+-- This version rolls back to the original output history on entering the+-- continuation.+liftCallCC :: CallCC m (a, w) (b, w) -> CallCC (AccumT w m) a b+liftCallCC callCC f = AccumT $ \ w ->+    callCC $ \ c ->+    runAccumT (f (\ a -> AccumT $ \ _ -> c (a, w))) w+{-# INLINE liftCallCC #-}++-- | In-situ lifting of a @callCC@ operation to the new monad.+-- This version uses the current output history on entering the continuation.+-- It does not satisfy the uniformity property (see "Control.Monad.Signatures").+liftCallCC' :: CallCC m (a, w) (b, w) -> CallCC (AccumT w m) a b+liftCallCC' callCC f = AccumT $ \ s ->+    callCC $ \ c ->+    runAccumT (f (\ a -> AccumT $ \ s' -> c (a, s'))) s+{-# INLINE liftCallCC' #-}++-- | Lift a @catchE@ operation to the new monad.+-- The uniformity property (see "Control.Monad.Signatures") implies that+-- the lifted @catchE@ discards any output from the body on entering+-- the handler.+liftCatch :: Catch e m (a, w) -> Catch e (AccumT w m) a+liftCatch catchE m h =+    AccumT $ \ w -> runAccumT m w `catchE` \ e -> runAccumT (h e) w+{-# INLINE liftCatch #-}++-- | Lift a @listen@ operation to the new monad.+liftListen :: (Monad m) => Listen w m (a, s) -> Listen w (AccumT s m) a+liftListen listen m = AccumT $ \ s -> do+    ~((a, s'), w) <- listen (runAccumT m s)+    return ((a, w), s')+{-# INLINE liftListen #-}++-- | Lift a @pass@ operation to the new monad.+liftPass :: (Monad m) => Pass w m (a, s) -> Pass w (AccumT s m) a+liftPass pass m = AccumT $ \ s -> pass $ do+    ~((a, f), s') <- runAccumT m s+    return ((a, s'), f)+{-# INLINE liftPass #-}++-- | Convert a read-only computation into an accumulation computation.+readerToAccumT :: (Functor m, Monoid w) => ReaderT w m a -> AccumT w m a+readerToAccumT (ReaderT f) = AccumT $ \ w -> fmap (\ a -> (a, mempty)) (f w)+{-# INLINE readerToAccumT #-}++-- | Convert a writer computation into an accumulation computation.+writerToAccumT :: WriterT w m a -> AccumT w m a+writerToAccumT (WriterT m) = AccumT $ const $ m+{-# INLINE writerToAccumT #-}++-- | Convert an accumulation (append-only) computation into a fully+-- stateful computation.+accumToStateT :: (Functor m, Monoid s) => AccumT s m a -> StateT s m a+accumToStateT (AccumT f) =+    StateT $ \ w -> fmap (\ ~(a, w') -> (a, w `mappend` w')) (f w)+{-# INLINE accumToStateT #-}
Control/Monad/Trans/Class.hs view
@@ -2,9 +2,12 @@ #if __GLASGOW_HASKELL__ >= 702 {-# LANGUAGE Safe #-} #endif-#if __GLASGOW_HASKELL__ >= 710+#if __GLASGOW_HASKELL__ >= 710 && __GLASGOW_HASKELL__ < 802 {-# LANGUAGE AutoDeriveTypeable #-} #endif+#if __GLASGOW_HASKELL__ >= 806+{-# LANGUAGE QuantifiedConstraints #-}+#endif ----------------------------------------------------------------------------- -- | -- Module      :  Control.Monad.Trans.Class@@ -46,38 +49,73 @@     -- $example3   ) where --- | The class of monad transformers.  Instances should satisfy the--- following laws, which state that 'lift' is a monad transformation:+-- | The class of monad transformers.+-- For any monad @m@, the result @t m@ should also be a monad,+-- and 'lift' should be a monad transformation from @m@ to @t m@,+-- i.e. it should satisfy the following laws: -- -- * @'lift' . 'return' = 'return'@ -- -- * @'lift' (m >>= f) = 'lift' m >>= ('lift' . f)@-+--+-- Since 0.6.0.0 and for GHC 8.6 and later, the requirement that @t m@+-- be a 'Monad' is enforced by the implication constraint+-- @forall m. 'Monad' m => 'Monad' (t m)@ enabled by the+-- @QuantifiedConstraints@ extension.+--+-- === __Ambiguity error with GHC 9.0 to 9.2.2__+-- These versions of GHC have a bug+-- (<https://gitlab.haskell.org/ghc/ghc/-/issues/20582>)+-- which causes constraints like+--+-- @+-- (MonadTrans t, forall m. Monad m => Monad (t m)) => ...+-- @+--+-- to be reported as ambiguous.  For transformers 0.6 and later, this can+-- be fixed by removing the second constraint, which is implied by the first.+#if __GLASGOW_HASKELL__ >= 806+class (forall m. Monad m => Monad (t m)) => MonadTrans t where+#else+-- Prior to GHC 8.8 (base-4.13), the Monad class included fail.+-- GHC 8.6 (base-4.12) has MonadFailDesugaring on by default, so there+-- is no need for users defining monad transformers to define fail in+-- the Monad instance of the transformed monad. class MonadTrans t where+#endif     -- | Lift a computation from the argument monad to the constructed monad.     lift :: (Monad m) => m a -> t m a  {- $conventions-Most monad transformer modules include the special case of applying-the transformer to 'Data.Functor.Identity.Identity'.  For example,+All monad transformer modules except 'Control.Monad.Trans.Maybe'+include the special case of applying the transformer+to 'Data.Functor.Identity.Identity'.  For example, @'Control.Monad.Trans.State.Lazy.State' s@ is an abbreviation for @'Control.Monad.Trans.State.Lazy.StateT' s 'Data.Functor.Identity.Identity'@.+As a consequence, operations defined on the monad transformer can also+be used on this special case.  Each monad transformer also comes with an operation @run@/XXX/@T@ to unwrap the transformer, exposing a computation of the inner monad.-(Currently these functions are defined as field labels, but in the next-major release they will be separate functions.)+(Currently these functions are defined as field labels, but in a future+major release they may be separate functions.)  All of the monad transformers except 'Control.Monad.Trans.Cont.ContT'-are functors on the category of monads: in addition to defining a-mapping of monads, they also define a mapping from transformations-between base monads to transformations between transformed monads,-called @map@/XXX/@T@.  Thus given a monad transformation @t :: M a -> N a@,-the combinator 'Control.Monad.Trans.State.Lazy.mapStateT' constructs-a monad transformation+and 'Control.Monad.Trans.Cont.SelectT' are functors on the category+of monads: in addition to defining a mapping of monads, they+also define a mapping from transformations between base monads to+transformations between transformed monads, called @map@/XXX/@T@.+Thus given a monad transformation @t :: M a -> N a@, the combinator+'Control.Monad.Trans.State.Lazy.mapStateT' constructs a monad+transformation  > mapStateT t :: StateT s M a -> StateT s N a +For these monad transformers, 'lift' is a natural transformation in the+category of monads, i.e. for any monad transformation @t :: M a -> N a@,++* @map@/XXX/@T t . 'lift' = 'lift' . t@+ Each of the monad transformers introduces relevant operations. In a sequence of monad transformers, most of these operations.can be lifted through other transformers using 'lift' or the @map@/XXX/@T@@@ -88,26 +126,39 @@  {- $strict -A monad is said to be /strict/ if its '>>=' operation is strict in its first-argument.  The base monads 'Maybe', @[]@ and 'IO' are strict:+A monad is said to be /strict/ if its '>>=' operation (and therefore also+'>>') is strict in its first argument.  The base monads 'Maybe', @[]@+and 'IO' are strict: ->>> undefined >> return 2 :: Maybe Integer+>>> undefined >> Just 2 *** Exception: Prelude.undefined+>>> undefined >> [2]+*** Exception: Prelude.undefined+>>> undefined >> print 2+*** Exception: Prelude.undefined -However the monad 'Data.Functor.Identity.Identity' is not:+However, the monads 'Data.Functor.Identity.Identity' and @(->) a@ are not: ->>> runIdentity (undefined >> return 2)-2+>>> undefined >> Identity 2+Identity 2+>>> (undefined >> (+1)) 5+6  In a strict monad you know when each action is executed, but the monad is not necessarily strict in the return value, or in other components-of the monad, such as a state.  However you can use 'seq' to create+of the monad, such as a state.  However, you can use 'seq' to create an action that is strict in the component you want evaluated. -}  {- $example1 -One might define a parsing monad by adding a state (the 'String' remaining+The first example is a parser monad in the style of++* \"Monadic parsing in Haskell\", by Graham Hutton and Erik Meijer,+/Journal of Functional Programming/ 8(4):437-444, July 1998+(<http://www.cs.nott.ac.uk/~pszgmh/bib.html#pearl>).++We can define such a parser monad by adding a state (the 'String' remaining to be parsed) to the @[]@ monad, which provides non-determinism:  > import Control.Monad.Trans.State@@ -183,7 +234,8 @@ {- $example3  This example is a cut-down version of the one in-\"Monad Transformers and Modular Interpreters\",++* \"Monad Transformers and Modular Interpreters\", by Sheng Liang, Paul Hudak and Mark Jones in /POPL'95/ (<http://web.cecs.pdx.edu/~mpj/pubs/modinterp.html>).
Control/Monad/Trans/Cont.hs view
@@ -1,11 +1,12 @@ {-# LANGUAGE CPP #-} #if __GLASGOW_HASKELL__ >= 702 {-# LANGUAGE Safe #-}+{-# LANGUAGE DeriveGeneric #-} #endif-#if __GLASGOW_HASKELL__ >= 704+#if __GLASGOW_HASKELL__ >= 706 {-# LANGUAGE PolyKinds #-} #endif-#if __GLASGOW_HASKELL__ >= 710+#if __GLASGOW_HASKELL__ >= 710 && __GLASGOW_HASKELL__ < 802 {-# LANGUAGE AutoDeriveTypeable #-} #endif -----------------------------------------------------------------------------@@ -52,15 +53,21 @@ import Control.Monad.Trans.Class import Data.Functor.Identity +#if !(MIN_VERSION_base(4,8,0)) import Control.Applicative+#endif #if MIN_VERSION_base(4,9,0) import qualified Control.Monad.Fail as Fail #endif+#if __GLASGOW_HASKELL__ >= 704+import GHC.Generics+#endif  {- |-Continuation monad.-@Cont r a@ is a CPS computation that produces an intermediate result-of type @a@ within a CPS computation whose final result type is @r@.+The continuation monad, which is non-strict.+@Cont r a@ is a CPS ("continuation-passing style") computation that produces an+intermediate result of type @a@ within a CPS computation whose final result type+is @r@.  The @return@ function simply creates a continuation which passes the value on. @@ -72,6 +79,7 @@ -- (The inverse of 'runCont') cont :: ((a -> r) -> r) -> Cont r a cont f = ContT (\ c -> Identity (f (runIdentity . c)))+{-# INLINE cont #-}  -- | The result of running a CPS computation with a given final continuation. -- (The inverse of 'cont')@@ -81,6 +89,7 @@                         -- the final result (often 'id').     -> r runCont m k = runIdentity (runContT m (Identity . k))+{-# INLINE runCont #-}  -- | The result of running a CPS computation with the identity as the -- final continuation.@@ -88,6 +97,7 @@ -- * @'evalCont' ('return' x) = x@ evalCont :: Cont r r -> r evalCont m = runIdentity (evalContT m)+{-# INLINE evalCont #-}  -- | Apply a function to transform the result of a continuation-passing -- computation.@@ -95,6 +105,7 @@ -- * @'runCont' ('mapCont' f m) = f . 'runCont' m@ mapCont :: (r -> r) -> Cont r a -> Cont r a mapCont f = mapContT (Identity . f . runIdentity)+{-# INLINE mapCont #-}  -- | Apply a function to transform the continuation passed to a CPS -- computation.@@ -102,6 +113,7 @@ -- * @'runCont' ('withCont' f m) = 'runCont' m . f@ withCont :: ((b -> r) -> (a -> r)) -> Cont r a -> Cont r b withCont f = withContT ((Identity .) . f . (runIdentity .))+{-# INLINE withCont #-}  -- | @'reset' m@ delimits the continuation of any 'shift' inside @m@. --@@ -109,6 +121,7 @@ -- reset :: Cont r r -> Cont r' r reset = resetT+{-# INLINE reset #-}  -- | @'shift' f@ captures the continuation up to the nearest enclosing -- 'reset' and passes it to @f@:@@ -117,10 +130,21 @@ -- shift :: ((a -> r) -> Cont r r) -> Cont r a shift f = shiftT (f . (runIdentity .))+{-# INLINE shift #-}  -- | The continuation monad transformer.--- Can be used to add continuation handling to other monads.+-- Can be used to add continuation handling to any type constructor:+-- the 'Monad' instance and most of the operations do not require @m@+-- to be a monad.+--+-- 'ContT' is not a functor on the category of monads, and many operations+-- cannot be lifted through it.+--+-- @ContT r m@ is strict if and only if @m@ is. newtype ContT r m a = ContT { runContT :: (a -> m r) -> m r }+#if __GLASGOW_HASKELL__ >= 704+    deriving (Generic)+#endif  -- | The result of running a CPS computation with 'return' as the -- final continuation.@@ -128,13 +152,17 @@ -- * @'evalContT' ('lift' m) = m@ evalContT :: (Monad m) => ContT r m r -> m r evalContT m = runContT m return+{-# INLINE evalContT #-}  -- | Apply a function to transform the result of a continuation-passing--- computation.+-- computation.  This has a more restricted type than the @map@ operations+-- for other monad transformers, because 'ContT' does not define a functor+-- in the category of monads. -- -- * @'runContT' ('mapContT' f m) = f . 'runContT' m@ mapContT :: (m r -> m r) -> ContT r m a -> ContT r m a mapContT f m = ContT $ f . runContT m+{-# INLINE mapContT #-}  -- | Apply a function to transform the continuation passed to a CPS -- computation.@@ -142,30 +170,41 @@ -- * @'runContT' ('withContT' f m) = 'runContT' m . f@ withContT :: ((b -> m r) -> (a -> m r)) -> ContT r m a -> ContT r m b withContT f m = ContT $ runContT m . f+{-# INLINE withContT #-}  instance Functor (ContT r m) where     fmap f m = ContT $ \ c -> runContT m (c . f)+    {-# INLINE fmap #-}  instance Applicative (ContT r m) where     pure x  = ContT ($ x)+    {-# INLINE pure #-}     f <*> v = ContT $ \ c -> runContT f $ \ g -> runContT v (c . g)+    {-# INLINE (<*>) #-}+    m *> k = m >>= \_ -> k+    {-# INLINE (*>) #-}  instance Monad (ContT r m) where #if !(MIN_VERSION_base(4,8,0))     return x = ContT ($ x)+    {-# INLINE return #-} #endif     m >>= k  = ContT $ \ c -> runContT m (\ x -> runContT (k x) c)+    {-# INLINE (>>=) #-}  #if MIN_VERSION_base(4,9,0) instance (Fail.MonadFail m) => Fail.MonadFail (ContT r m) where     fail msg = ContT $ \ _ -> Fail.fail msg+    {-# INLINE fail #-} #endif  instance MonadTrans (ContT r) where     lift m = ContT (m >>=)+    {-# INLINE lift #-}  instance (MonadIO m) => MonadIO (ContT r m) where     liftIO = lift . liftIO+    {-# INLINE liftIO #-}  -- | @callCC@ (call-with-current-continuation) calls its argument -- function, passing it the current continuation.  It provides@@ -184,6 +223,7 @@ -- layers deep within nested computations. callCC :: ((a -> ContT r m b) -> ContT r m a) -> ContT r m a callCC f = ContT $ \ c -> runContT (f (\ x -> ContT $ \ _ -> c x)) c+{-# INLINE callCC #-}  -- | @'resetT' m@ delimits the continuation of any 'shiftT' inside @m@. --@@ -191,6 +231,7 @@ -- resetT :: (Monad m) => ContT r m r -> ContT r' m r resetT = lift . evalContT+{-# INLINE resetT #-}  -- | @'shiftT' f@ captures the continuation up to the nearest enclosing -- 'resetT' and passes it to @f@:@@ -199,6 +240,7 @@ -- shiftT :: (Monad m) => ((a -> m r) -> ContT r m r) -> ContT r m a shiftT f = ContT (evalContT . f)+{-# INLINE shiftT #-}  -- | @'liftLocal' ask local@ yields a @local@ function for @'ContT' r m@. liftLocal :: (Monad m) => m r' -> ((r' -> r') -> m r -> m r) ->@@ -206,3 +248,4 @@ liftLocal ask local f m = ContT $ \ c -> do     r <- ask     local f (runContT m (local (const r) . c))+{-# INLINE liftLocal #-}
− Control/Monad/Trans/Error.hs 
@@ -1,323 +0,0 @@-{-# LANGUAGE CPP #-}-#if __GLASGOW_HASKELL__ >= 702-{-# LANGUAGE Safe #-}-#endif-#if __GLASGOW_HASKELL__ >= 710-{-# LANGUAGE AutoDeriveTypeable #-}-#endif-#if !(MIN_VERSION_base(4,9,0))-{-# OPTIONS_GHC -fno-warn-orphans #-}-#endif--------------------------------------------------------------------------------- |--- Module      :  Control.Monad.Trans.Error--- Copyright   :  (c) Michael Weber <michael.weber@post.rwth-aachen.de> 2001,---                (c) Jeff Newbern 2003-2006,---                (c) Andriy Palamarchuk 2006--- License     :  BSD-style (see the file LICENSE)------ Maintainer  :  R.Paterson@city.ac.uk--- Stability   :  experimental--- Portability :  portable------ This monad transformer adds the ability to fail or throw exceptions--- to a monad.------ A sequence of actions succeeds, producing a value, only if all the--- actions in the sequence are successful.  If one fails with an error,--- the rest of the sequence is skipped and the composite action fails--- with that error.------ If the value of the error is not required, the variant in--- "Control.Monad.Trans.Maybe" may be used instead.------ /Note:/ This module will be removed in a future release.--- Instead, use "Control.Monad.Trans.Except", which does not restrict--- the exception type, and also includes a base exception monad.--------------------------------------------------------------------------------module Control.Monad.Trans.Error-  {-# DEPRECATED "Use Control.Monad.Trans.Except instead" #-} (-    -- * The ErrorT monad transformer-    Error(..),-    ErrorList(..),-    ErrorT(..),-    mapErrorT,-    -- * Error operations-    throwError,-    catchError,-    -- * Lifting other operations-    liftCallCC,-    liftListen,-    liftPass,-    -- * Examples-    -- $examples-  ) where--import Control.Monad.IO.Class-import Control.Monad.Signatures-import Control.Monad.Trans.Class-import Data.Functor.Classes--import Control.Applicative-import Control.Exception (IOException)-import Control.Monad-#if MIN_VERSION_base(4,9,0)-import qualified Control.Monad.Fail as Fail-#endif-import Control.Monad.Fix-#if !(MIN_VERSION_base(4,6,0))-import Control.Monad.Instances ()  -- deprecated from base-4.6-#endif-import Data.Foldable (Foldable(foldMap))-import Data.Monoid (mempty)-import Data.Traversable (Traversable(traverse))-import System.IO.Error--#if !(MIN_VERSION_base(4,9,0))--- These instances are in base-4.9.0--instance MonadPlus IO where-    mzero       = ioError (userError "mzero")-    m `mplus` n = m `catchIOError` \ _ -> n--instance Alternative IO where-    empty = mzero-    (<|>) = mplus--# if !(MIN_VERSION_base(4,4,0))--- exported by System.IO.Error from base-4.4-catchIOError :: IO a -> (IOError -> IO a) -> IO a-catchIOError = catch-# endif--instance (Error e) => Alternative (Either e) where-    empty        = Left noMsg-    Left _ <|> n = n-    m      <|> _ = m--instance (Error e) => MonadPlus (Either e) where-    mzero            = Left noMsg-    Left _ `mplus` n = n-    m      `mplus` _ = m-#endif--#if !(MIN_VERSION_base(4,3,0))--- These instances are in base-4.3--instance Applicative (Either e) where-    pure          = Right-    Left  e <*> _ = Left e-    Right f <*> r = fmap f r--instance Monad (Either e) where-    return        = Right-    Left  l >>= _ = Left l-    Right r >>= k = k r--instance MonadFix (Either e) where-    mfix f = let-        a = f $ case a of-            Right r -> r-            _       -> error "empty mfix argument"-        in a--#endif /* base to 4.2.0.x */---- | An exception to be thrown.------ Minimal complete definition: 'noMsg' or 'strMsg'.-class Error a where-    -- | Creates an exception without a message.-    -- The default implementation is @'strMsg' \"\"@.-    noMsg  :: a-    -- | Creates an exception with a message.-    -- The default implementation of @'strMsg' s@ is 'noMsg'.-    strMsg :: String -> a--    noMsg    = strMsg ""-    strMsg _ = noMsg--instance Error IOException where-    strMsg = userError---- | A string can be thrown as an error.-instance (ErrorList a) => Error [a] where-    strMsg = listMsg---- | Workaround so that we can have a Haskell 98 instance @'Error' 'String'@.-class ErrorList a where-    listMsg :: String -> [a]--instance ErrorList Char where-    listMsg = id---- | The error monad transformer. It can be used to add error handling--- to other monads.------ The @ErrorT@ Monad structure is parameterized over two things:------ * e - The error type.------ * m - The inner monad.------ The 'return' function yields a successful computation, while @>>=@--- sequences two subcomputations, failing on the first error.-newtype ErrorT e m a = ErrorT { runErrorT :: m (Either e a) }--instance (Eq e, Eq1 m) => Eq1 (ErrorT e m) where-    liftEq eq (ErrorT x) (ErrorT y) = liftEq (liftEq eq) x y--instance (Ord e, Ord1 m) => Ord1 (ErrorT e m) where-    liftCompare comp (ErrorT x) (ErrorT y) = liftCompare (liftCompare comp) x y--instance (Read e, Read1 m) => Read1 (ErrorT e m) where-    liftReadsPrec rp rl = readsData $-        readsUnaryWith (liftReadsPrec rp' rl') "ErrorT" ErrorT-      where-        rp' = liftReadsPrec rp rl-        rl' = liftReadList rp rl--instance (Show e, Show1 m) => Show1 (ErrorT e m) where-    liftShowsPrec sp sl d (ErrorT m) =-        showsUnaryWith (liftShowsPrec sp' sl') "ErrorT" d m-      where-        sp' = liftShowsPrec sp sl-        sl' = liftShowList sp sl--instance (Eq e, Eq1 m, Eq a) => Eq (ErrorT e m a) where (==) = eq1-instance (Ord e, Ord1 m, Ord a) => Ord (ErrorT e m a) where compare = compare1-instance (Read e, Read1 m, Read a) => Read (ErrorT e m a) where-    readsPrec = readsPrec1-instance (Show e, Show1 m, Show a) => Show (ErrorT e m a) where-    showsPrec = showsPrec1---- | Map the unwrapped computation using the given function.------ * @'runErrorT' ('mapErrorT' f m) = f ('runErrorT' m)@-mapErrorT :: (m (Either e a) -> n (Either e' b))-          -> ErrorT e m a-          -> ErrorT e' n b-mapErrorT f m = ErrorT $ f (runErrorT m)--instance (Functor m) => Functor (ErrorT e m) where-    fmap f = ErrorT . fmap (fmap f) . runErrorT--instance (Foldable f) => Foldable (ErrorT e f) where-    foldMap f (ErrorT a) = foldMap (either (const mempty) f) a--instance (Traversable f) => Traversable (ErrorT e f) where-    traverse f (ErrorT a) =-        ErrorT <$> traverse (either (pure . Left) (fmap Right . f)) a--instance (Functor m, Monad m) => Applicative (ErrorT e m) where-    pure a  = ErrorT $ return (Right a)-    f <*> v = ErrorT $ do-        mf <- runErrorT f-        case mf of-            Left  e -> return (Left e)-            Right k -> do-                mv <- runErrorT v-                case mv of-                    Left  e -> return (Left e)-                    Right x -> return (Right (k x))--instance (Functor m, Monad m, Error e) => Alternative (ErrorT e m) where-    empty = mzero-    (<|>) = mplus--instance (Monad m, Error e) => Monad (ErrorT e m) where-#if !(MIN_VERSION_base(4,8,0))-    return a = ErrorT $ return (Right a)-#endif-    m >>= k  = ErrorT $ do-        a <- runErrorT m-        case a of-            Left  l -> return (Left l)-            Right r -> runErrorT (k r)-    fail msg = ErrorT $ return (Left (strMsg msg))--#if MIN_VERSION_base(4,9,0)-instance (Monad m, Error e) => Fail.MonadFail (ErrorT e m) where-    fail msg = ErrorT $ return (Left (strMsg msg))-#endif--instance (Monad m, Error e) => MonadPlus (ErrorT e m) where-    mzero       = ErrorT $ return (Left noMsg)-    m `mplus` n = ErrorT $ do-        a <- runErrorT m-        case a of-            Left  _ -> runErrorT n-            Right r -> return (Right r)--instance (MonadFix m, Error e) => MonadFix (ErrorT e m) where-    mfix f = ErrorT $ mfix $ \ a -> runErrorT $ f $ case a of-        Right r -> r-        _       -> error "empty mfix argument"--instance MonadTrans (ErrorT e) where-    lift m = ErrorT $ do-        a <- m-        return (Right a)--instance (Error e, MonadIO m) => MonadIO (ErrorT e m) where-    liftIO = lift . liftIO---- | Signal an error value @e@.------ * @'runErrorT' ('throwError' e) = 'return' ('Left' e)@------ * @'throwError' e >>= m = 'throwError' e@-throwError :: (Monad m) => e -> ErrorT e m a-throwError l = ErrorT $ return (Left l)---- | Handle an error.------ * @'catchError' h ('lift' m) = 'lift' m@------ * @'catchError' h ('throwError' e) = h e@-catchError :: (Monad m) =>-    ErrorT e m a                -- ^ the inner computation-    -> (e -> ErrorT e m a)      -- ^ a handler for errors in the inner-                                -- computation-    -> ErrorT e m a-m `catchError` h = ErrorT $ do-    a <- runErrorT m-    case a of-        Left  l -> runErrorT (h l)-        Right r -> return (Right r)---- | Lift a @callCC@ operation to the new monad.-liftCallCC :: CallCC m (Either e a) (Either e b) -> CallCC (ErrorT e m) a b-liftCallCC callCC f = ErrorT $-    callCC $ \ c ->-    runErrorT (f (\ a -> ErrorT $ c (Right a)))---- | Lift a @listen@ operation to the new monad.-liftListen :: (Monad m) => Listen w m (Either e a) -> Listen w (ErrorT e m) a-liftListen listen = mapErrorT $ \ m -> do-    (a, w) <- listen m-    return $! fmap (\ r -> (r, w)) a---- | Lift a @pass@ operation to the new monad.-liftPass :: (Monad m) => Pass w m (Either e a) -> Pass w (ErrorT e m) a-liftPass pass = mapErrorT $ \ m -> pass $ do-    a <- m-    return $! case a of-        Left  l      -> (Left  l, id)-        Right (r, f) -> (Right r, f)--{- $examples--Wrapping an IO action that can throw an error @e@:--> type ErrorWithIO e a = ErrorT e IO a-> ==> ErrorT (IO (Either e a))--An IO monad wrapped in @StateT@ inside of @ErrorT@:--> type ErrorAndStateWithIO e s a = ErrorT e (StateT s IO) a-> ==> ErrorT (StateT s IO (Either e a))-> ==> ErrorT (StateT (s -> IO (Either e a,s)))---}
Control/Monad/Trans/Except.hs view
@@ -1,8 +1,9 @@ {-# LANGUAGE CPP #-} #if __GLASGOW_HASKELL__ >= 702 {-# LANGUAGE Safe #-}+{-# LANGUAGE DeriveGeneric #-} #endif-#if __GLASGOW_HASKELL__ >= 710+#if __GLASGOW_HASKELL__ >= 710 && __GLASGOW_HASKELL__ < 802 {-# LANGUAGE AutoDeriveTypeable #-} #endif -----------------------------------------------------------------------------@@ -15,7 +16,8 @@ -- Stability   :  experimental -- Portability :  portable ----- This monad transformer extends a monad with the ability throw exceptions.+-- This monad transformer extends a monad with the ability to throw+-- and catch exceptions. -- -- A sequence of actions terminates normally, producing a value, -- only if none of the actions in the sequence throws an exception.@@ -34,13 +36,16 @@     mapExcept,     withExcept,     -- * The ExceptT monad transformer-    ExceptT(ExceptT),-    runExceptT,+    ExceptT(..),     mapExceptT,     withExceptT,     -- * Exception operations     throwE,     catchE,+    handleE,+    tryE,+    finallyE,+    onE,     -- * Lifting other operations     liftCallCC,     liftListen,@@ -51,6 +56,9 @@ import Control.Monad.Signatures import Control.Monad.Trans.Class import Data.Functor.Classes+#if MIN_VERSION_base(4,12,0)+import Data.Functor.Contravariant+#endif import Data.Functor.Identity  import Control.Applicative@@ -62,13 +70,20 @@ #if MIN_VERSION_base(4,4,0) import Control.Monad.Zip (MonadZip(mzipWith)) #endif+#if !(MIN_VERSION_base(4,8,0)) || defined(__MHS__) import Data.Foldable (Foldable(foldMap))-import Data.Monoid+import Data.Monoid (Monoid(mempty, mappend)) import Data.Traversable (Traversable(traverse))+#endif+#if __GLASGOW_HASKELL__ >= 704+import GHC.Generics+#endif --- | The parameterizable exception monad.+-- | The parameterizable exception monad, which is strict. ----- Computations are either exceptions or normal values.+-- Computations are either exceptions (of any type) or normal values.+-- These computations are plain values, and are unrelated to the+-- "Control.Exception" mechanism, which is tied to the 'IO' monad. -- -- The 'return' function returns a normal value, while @>>=@ exits on -- the first exception.  For a variant that continues after an error@@ -77,13 +92,15 @@  -- | Constructor for computations in the exception monad. -- (The inverse of 'runExcept').-except :: Either e a -> Except e a-except m = ExceptT (Identity m)+except :: (Monad m) => Either e a -> ExceptT e m a+except m = ExceptT (return m)+{-# INLINE except #-}  -- | Extractor for computations in the exception monad. -- (The inverse of 'except'). runExcept :: Except e a -> Either e a runExcept (ExceptT m) = runIdentity m+{-# INLINE runExcept #-}  -- | Map the unwrapped computation using the given function. --@@ -92,31 +109,43 @@         -> Except e a         -> Except e' b mapExcept f = mapExceptT (Identity . f . runIdentity)+{-# INLINE mapExcept #-}  -- | Transform any exceptions thrown by the computation using the given -- function (a specialization of 'withExceptT'). withExcept :: (e -> e') -> Except e a -> Except e' a withExcept = withExceptT+{-# INLINE withExcept #-}  -- | A monad transformer that adds exceptions to other monads. ----- @ExceptT@ constructs a monad parameterized over two things:+-- @ExceptT@ constructs a strict monad parameterized over two things: ----- * e - The exception type.+-- * e - An arbitrary exception type. -- -- * m - The inner monad. --+-- The monadic computations are a plain values.  They are unrelated to+-- the "Control.Exception" mechanism, which is tied to the 'IO' monad.+-- -- The 'return' function yields a computation that produces the given -- value, while @>>=@ sequences two subcomputations, exiting on the -- first exception.-newtype ExceptT e m a = ExceptT (m (Either e a))+newtype ExceptT e m a = ExceptT { runExceptT :: m (Either e a) }+#if __GLASGOW_HASKELL__ >= 710+    deriving (Generic, Generic1)+#elif __GLASGOW_HASKELL__ >= 704+    deriving (Generic)+#endif  instance (Eq e, Eq1 m) => Eq1 (ExceptT e m) where     liftEq eq (ExceptT x) (ExceptT y) = liftEq (liftEq eq) x y+    {-# INLINE liftEq #-}  instance (Ord e, Ord1 m) => Ord1 (ExceptT e m) where     liftCompare comp (ExceptT x) (ExceptT y) =         liftCompare (liftCompare comp) x y+    {-# INLINE liftCompare #-}  instance (Read e, Read1 m) => Read1 (ExceptT e m) where     liftReadsPrec rp rl = readsData $@@ -132,17 +161,15 @@         sp' = liftShowsPrec sp sl         sl' = liftShowList sp sl -instance (Eq e, Eq1 m, Eq a) => Eq (ExceptT e m a) where (==) = eq1-instance (Ord e, Ord1 m, Ord a) => Ord (ExceptT e m a) where compare = compare1+instance (Eq e, Eq1 m, Eq a) => Eq (ExceptT e m a)+    where (==) = eq1+instance (Ord e, Ord1 m, Ord a) => Ord (ExceptT e m a)+    where compare = compare1 instance (Read e, Read1 m, Read a) => Read (ExceptT e m a) where     readsPrec = readsPrec1 instance (Show e, Show1 m, Show a) => Show (ExceptT e m a) where     showsPrec = showsPrec1 --- | The inverse of 'ExceptT'.-runExceptT :: ExceptT e m a -> m (Either e a)-runExceptT (ExceptT m) = m- -- | Map the unwrapped computation using the given function. -- -- * @'runExceptT' ('mapExceptT' f m) = f ('runExceptT' m)@@@ -150,24 +177,30 @@         -> ExceptT e m a         -> ExceptT e' n b mapExceptT f m = ExceptT $ f (runExceptT m)+{-# INLINE mapExceptT #-}  -- | Transform any exceptions thrown by the computation using the -- given function. withExceptT :: (Functor m) => (e -> e') -> ExceptT e m a -> ExceptT e' m a withExceptT f = mapExceptT $ fmap $ either (Left . f) Right+{-# INLINE withExceptT #-}  instance (Functor m) => Functor (ExceptT e m) where     fmap f = ExceptT . fmap (fmap f) . runExceptT+    {-# INLINE fmap #-}  instance (Foldable f) => Foldable (ExceptT e f) where     foldMap f (ExceptT a) = foldMap (either (const mempty) f) a+    {-# INLINE foldMap #-}  instance (Traversable f) => Traversable (ExceptT e f) where     traverse f (ExceptT a) =         ExceptT <$> traverse (either (pure . Left) (fmap Right . f)) a+    {-# INLINE traverse #-}  instance (Functor m, Monad m) => Applicative (ExceptT e m) where     pure a = ExceptT $ return (Right a)+    {-# INLINE pure #-}     ExceptT f <*> ExceptT v = ExceptT $ do         mf <- f         case mf of@@ -177,54 +210,77 @@                 case mv of                     Left e -> return (Left e)                     Right x -> return (Right (k x))+    {-# INLINEABLE (<*>) #-}+    m *> k = m >>= \_ -> k+    {-# INLINE (*>) #-}  instance (Functor m, Monad m, Monoid e) => Alternative (ExceptT e m) where     empty = ExceptT $ return (Left mempty)+    {-# INLINE empty #-}     ExceptT mx <|> ExceptT my = ExceptT $ do         ex <- mx         case ex of             Left e -> liftM (either (Left . mappend e) Right) my             Right x -> return (Right x)+    {-# INLINEABLE (<|>) #-}  instance (Monad m) => Monad (ExceptT e m) where #if !(MIN_VERSION_base(4,8,0))     return a = ExceptT $ return (Right a)+    {-# INLINE return #-} #endif     m >>= k = ExceptT $ do         a <- runExceptT m         case a of             Left e -> return (Left e)             Right x -> runExceptT (k x)+    {-# INLINE (>>=) #-}+#if !(MIN_VERSION_base(4,13,0))     fail = ExceptT . fail+    {-# INLINE fail #-}+#endif  #if MIN_VERSION_base(4,9,0) instance (Fail.MonadFail m) => Fail.MonadFail (ExceptT e m) where     fail = ExceptT . Fail.fail+    {-# INLINE fail #-} #endif  instance (Monad m, Monoid e) => MonadPlus (ExceptT e m) where     mzero = ExceptT $ return (Left mempty)+    {-# INLINE mzero #-}     ExceptT mx `mplus` ExceptT my = ExceptT $ do         ex <- mx         case ex of             Left e -> liftM (either (Left . mappend e) Right) my             Right x -> return (Right x)+    {-# INLINEABLE mplus #-}  instance (MonadFix m) => MonadFix (ExceptT e m) where     mfix f = ExceptT (mfix (runExceptT . f . either (const bomb) id))       where bomb = error "mfix (ExceptT): inner computation returned Left value"+    {-# INLINE mfix #-}  instance MonadTrans (ExceptT e) where     lift = ExceptT . liftM Right+    {-# INLINE lift #-}  instance (MonadIO m) => MonadIO (ExceptT e m) where     liftIO = lift . liftIO+    {-# INLINE liftIO #-}  #if MIN_VERSION_base(4,4,0) instance (MonadZip m) => MonadZip (ExceptT e m) where     mzipWith f (ExceptT a) (ExceptT b) = ExceptT $ mzipWith (liftA2 f) a b+    {-# INLINE mzipWith #-} #endif +#if MIN_VERSION_base(4,12,0)+instance Contravariant m => Contravariant (ExceptT e m) where+    contramap f = ExceptT . contramap (fmap f) . runExceptT+    {-# INLINE contramap #-}+#endif+ -- | Signal an exception value @e@. -- -- * @'runExceptT' ('throwE' e) = 'return' ('Left' e)@@@ -232,12 +288,13 @@ -- * @'throwE' e >>= m = 'throwE' e@ throwE :: (Monad m) => e -> ExceptT e m a throwE = ExceptT . return . Left+{-# INLINE throwE #-}  -- | Handle an exception. ----- * @'catchE' h ('lift' m) = 'lift' m@+-- * @'catchE' ('lift' m) h = 'lift' m@ ----- * @'catchE' h ('throwE' e) = h e@+-- * @'catchE' ('throwE' e) h = h e@ catchE :: (Monad m) =>     ExceptT e m a               -- ^ the inner computation     -> (e -> ExceptT e' m a)    -- ^ a handler for exceptions in the inner@@ -248,18 +305,52 @@     case a of         Left  l -> runExceptT (h l)         Right r -> return (Right r)+{-# INLINE catchE #-} +-- | The same as @'flip' 'catchE'@, which is useful in situations where+-- the code for the handler is shorter.+handleE :: Monad m => (e -> ExceptT e' m a) -> ExceptT e m a -> ExceptT e' m a+handleE = flip catchE+{-# INLINE handleE #-}++-- | Similar to 'catchE', but returns an 'Either' result which is+-- @('Right' a)@ if no exception was thown, or @('Left' ex)@ if an+-- exception @ex@ was thrown.+tryE :: Monad m => ExceptT e m a -> ExceptT e m (Either e a)+tryE m = catchE (liftM Right m) (return . Left)+{-# INLINE tryE #-}++-- | @'finallyE' a b@ executes computation @a@ followed by computation @b@,+-- even if @a@ exits early by throwing an exception.  In the latter case,+-- the exception is re-thrown after @b@ has been executed.+finallyE :: Monad m => ExceptT e m a -> ExceptT e m () -> ExceptT e m a+finallyE m closer = do+    res <- tryE m+    closer+    either throwE return res+{-# INLINE finallyE #-}++-- | If the first action succeeds, return its value, ignoring the+-- second action.  If the first action throws an exception, run the+-- second action and then throw an exception, either the one thrown by+-- the second action, if any, or the one thrown by the first action.+onE :: (Monad m) => ExceptT e m a -> ExceptT e m b -> ExceptT e m a+onE action1 action2 = action1 `catchE` \ e -> action2 >> throwE e+{-# INLINE onE #-}+ -- | Lift a @callCC@ operation to the new monad. liftCallCC :: CallCC m (Either e a) (Either e b) -> CallCC (ExceptT e m) a b liftCallCC callCC f = ExceptT $     callCC $ \ c ->     runExceptT (f (\ a -> ExceptT $ c (Right a)))+{-# INLINE liftCallCC #-}  -- | Lift a @listen@ operation to the new monad. liftListen :: (Monad m) => Listen w m (Either e a) -> Listen w (ExceptT e m) a liftListen listen = mapExceptT $ \ m -> do     (a, w) <- listen m     return $! fmap (\ r -> (r, w)) a+{-# INLINE liftListen #-}  -- | Lift a @pass@ operation to the new monad. liftPass :: (Monad m) => Pass w m (Either e a) -> Pass w (ExceptT e m) a@@ -268,3 +359,4 @@     return $! case a of         Left l -> (Left l, id)         Right (r, f) -> (Right r, f)+{-# INLINE liftPass #-}
Control/Monad/Trans/Identity.hs view
@@ -1,11 +1,12 @@ {-# LANGUAGE CPP #-} #if __GLASGOW_HASKELL__ >= 702 {-# LANGUAGE Safe #-}+{-# LANGUAGE DeriveGeneric #-} #endif-#if __GLASGOW_HASKELL__ >= 704+#if __GLASGOW_HASKELL__ >= 706 {-# LANGUAGE PolyKinds #-} #endif-#if __GLASGOW_HASKELL__ >= 710+#if __GLASGOW_HASKELL__ >= 710 && __GLASGOW_HASKELL__ < 802 {-# LANGUAGE AutoDeriveTypeable #-} #endif -----------------------------------------------------------------------------@@ -35,7 +36,13 @@ import Control.Monad.IO.Class (MonadIO(liftIO)) import Control.Monad.Signatures import Control.Monad.Trans.Class (MonadTrans(lift))+#if MIN_VERSION_base(4,18,0)+import Data.Foldable1 (Foldable1(foldMap1))+#endif import Data.Functor.Classes+#if MIN_VERSION_base(4,12,0)+import Data.Functor.Contravariant+#endif  import Control.Applicative import Control.Monad (MonadPlus(mzero, mplus))@@ -46,17 +53,30 @@ #if MIN_VERSION_base(4,4,0) import Control.Monad.Zip (MonadZip(mzipWith)) #endif-import Data.Foldable (Foldable(foldMap))+import Data.Foldable+#if !(MIN_VERSION_base(4,8,0)) || defined(__MHS__) import Data.Traversable (Traversable(traverse))+#endif+import Prelude hiding (foldr, foldr1, foldl, foldl1, null, length)+#if __GLASGOW_HASKELL__ >= 704+import GHC.Generics+#endif  -- | The trivial monad transformer, which maps a monad to an equivalent monad. newtype IdentityT f a = IdentityT { runIdentityT :: f a }+#if __GLASGOW_HASKELL__ >= 710+    deriving (Generic, Generic1)+#elif __GLASGOW_HASKELL__ >= 704+    deriving (Generic)+#endif  instance (Eq1 f) => Eq1 (IdentityT f) where     liftEq eq (IdentityT x) (IdentityT y) = liftEq eq x y+    {-# INLINE liftEq #-}  instance (Ord1 f) => Ord1 (IdentityT f) where     liftCompare comp (IdentityT x) (IdentityT y) = liftCompare comp x y+    {-# INLINE liftCompare #-}  instance (Read1 f) => Read1 (IdentityT f) where     liftReadsPrec rp rl = readsData $@@ -73,65 +93,116 @@  instance (Functor m) => Functor (IdentityT m) where     fmap f = mapIdentityT (fmap f)+    {-# INLINE fmap #-}  instance (Foldable f) => Foldable (IdentityT f) where-    foldMap f (IdentityT a) = foldMap f a+    foldMap f (IdentityT t) = foldMap f t+    {-# INLINE foldMap #-}+    foldr f z (IdentityT t) = foldr f z t+    {-# INLINE foldr #-}+    foldl f z (IdentityT t) = foldl f z t+    {-# INLINE foldl #-}+    foldr1 f (IdentityT t) = foldr1 f t+    {-# INLINE foldr1 #-}+    foldl1 f (IdentityT t) = foldl1 f t+    {-# INLINE foldl1 #-}+#if MIN_VERSION_base(4,8,0)+    null (IdentityT t) = null t+    length (IdentityT t) = length t+#endif +#if MIN_VERSION_base(4,18,0)+instance (Foldable1 m) => Foldable1 (IdentityT m) where+    foldMap1 f (IdentityT t) = foldMap1 f t+    {-# INLINE foldMap1 #-}+#endif+ instance (Traversable f) => Traversable (IdentityT f) where     traverse f (IdentityT a) = IdentityT <$> traverse f a+    {-# INLINE traverse #-}  instance (Applicative m) => Applicative (IdentityT m) where     pure x = IdentityT (pure x)+    {-# INLINE pure #-}     (<*>) = lift2IdentityT (<*>)+    {-# INLINE (<*>) #-}+    (*>) = lift2IdentityT (*>)+    {-# INLINE (*>) #-}+    (<*) = lift2IdentityT (<*)+    {-# INLINE (<*) #-}  instance (Alternative m) => Alternative (IdentityT m) where     empty = IdentityT empty+    {-# INLINE empty #-}     (<|>) = lift2IdentityT (<|>)+    {-# INLINE (<|>) #-}  instance (Monad m) => Monad (IdentityT m) where #if !(MIN_VERSION_base(4,8,0))     return = IdentityT . return+    {-# INLINE return #-} #endif     m >>= k = IdentityT $ runIdentityT . k =<< runIdentityT m+    {-# INLINE (>>=) #-}+#if !(MIN_VERSION_base(4,13,0))     fail msg = IdentityT $ fail msg+    {-# INLINE fail #-}+#endif  #if MIN_VERSION_base(4,9,0) instance (Fail.MonadFail m) => Fail.MonadFail (IdentityT m) where     fail msg = IdentityT $ Fail.fail msg+    {-# INLINE fail #-} #endif  instance (MonadPlus m) => MonadPlus (IdentityT m) where     mzero = IdentityT mzero+    {-# INLINE mzero #-}     mplus = lift2IdentityT mplus+    {-# INLINE mplus #-}  instance (MonadFix m) => MonadFix (IdentityT m) where     mfix f = IdentityT (mfix (runIdentityT . f))+    {-# INLINE mfix #-}  instance (MonadIO m) => MonadIO (IdentityT m) where     liftIO = IdentityT . liftIO+    {-# INLINE liftIO #-}  #if MIN_VERSION_base(4,4,0) instance (MonadZip m) => MonadZip (IdentityT m) where     mzipWith f = lift2IdentityT (mzipWith f)+    {-# INLINE mzipWith #-} #endif  instance MonadTrans IdentityT where     lift = IdentityT+    {-# INLINE lift #-} +#if MIN_VERSION_base(4,12,0)+instance (Contravariant f) => Contravariant (IdentityT f) where+    contramap f = IdentityT . contramap f . runIdentityT+    {-# INLINE contramap #-}+#endif+ -- | Lift a unary operation to the new monad. mapIdentityT :: (m a -> n b) -> IdentityT m a -> IdentityT n b mapIdentityT f = IdentityT . f . runIdentityT+{-# INLINE mapIdentityT #-}  -- | Lift a binary operation to the new monad. lift2IdentityT ::     (m a -> n b -> p c) -> IdentityT m a -> IdentityT n b -> IdentityT p c lift2IdentityT f a b = IdentityT (f (runIdentityT a) (runIdentityT b))+{-# INLINE lift2IdentityT #-}  -- | Lift a @callCC@ operation to the new monad. liftCallCC :: CallCC m a b -> CallCC (IdentityT m) a b liftCallCC callCC f =     IdentityT $ callCC $ \ c -> runIdentityT (f (IdentityT . c))+{-# INLINE liftCallCC #-}  -- | Lift a @catchE@ operation to the new monad. liftCatch :: Catch e m a -> Catch e (IdentityT m) a liftCatch f m h = IdentityT $ f (runIdentityT m) (runIdentityT . h)+{-# INLINE liftCatch #-}
− Control/Monad/Trans/List.hs 
@@ -1,145 +0,0 @@-{-# LANGUAGE CPP #-}-#if __GLASGOW_HASKELL__ >= 702-{-# LANGUAGE Safe #-}-#endif-#if __GLASGOW_HASKELL__ >= 710-{-# LANGUAGE AutoDeriveTypeable #-}-#endif--------------------------------------------------------------------------------- |--- Module      :  Control.Monad.Trans.List--- Copyright   :  (c) Andy Gill 2001,---                (c) Oregon Graduate Institute of Science and Technology, 2001--- License     :  BSD-style (see the file LICENSE)------ Maintainer  :  R.Paterson@city.ac.uk--- Stability   :  experimental--- Portability :  portable------ The ListT monad transformer, adding backtracking to a given monad,--- which must be commutative.--------------------------------------------------------------------------------module Control.Monad.Trans.List (-    -- * The ListT monad transformer-    ListT(..),-    mapListT,-    -- * Lifting other operations-    liftCallCC,-    liftCatch,-  ) where--import Control.Monad.IO.Class-import Control.Monad.Signatures-import Control.Monad.Trans.Class-import Data.Functor.Classes--import Control.Applicative-import Control.Monad-#if MIN_VERSION_base(4,9,0)-import qualified Control.Monad.Fail as Fail-#endif-#if MIN_VERSION_base(4,4,0)-import Control.Monad.Zip (MonadZip(mzipWith))-#endif-import Data.Foldable (Foldable(foldMap))-import Data.Traversable (Traversable(traverse))---- | Parameterizable list monad, with an inner monad.------ /Note:/ this does not yield a monad unless the argument monad is commutative.-newtype ListT m a = ListT { runListT :: m [a] }--instance (Eq1 m) => Eq1 (ListT m) where-    liftEq eq (ListT x) (ListT y) = liftEq (liftEq eq) x y--instance (Ord1 m) => Ord1 (ListT m) where-    liftCompare comp (ListT x) (ListT y) = liftCompare (liftCompare comp) x y--instance (Read1 m) => Read1 (ListT m) where-    liftReadsPrec rp rl = readsData $-        readsUnaryWith (liftReadsPrec rp' rl') "ListT" ListT-      where-        rp' = liftReadsPrec rp rl-        rl' = liftReadList rp rl--instance (Show1 m) => Show1 (ListT m) where-    liftShowsPrec sp sl d (ListT m) =-        showsUnaryWith (liftShowsPrec sp' sl') "ListT" d m-      where-        sp' = liftShowsPrec sp sl-        sl' = liftShowList sp sl--instance (Eq1 m, Eq a) => Eq (ListT m a) where (==) = eq1-instance (Ord1 m, Ord a) => Ord (ListT m a) where compare = compare1-instance (Read1 m, Read a) => Read (ListT m a) where readsPrec = readsPrec1-instance (Show1 m, Show a) => Show (ListT m a) where showsPrec = showsPrec1---- | Map between 'ListT' computations.------ * @'runListT' ('mapListT' f m) = f ('runListT' m)@-mapListT :: (m [a] -> n [b]) -> ListT m a -> ListT n b-mapListT f m = ListT $ f (runListT m)--instance (Functor m) => Functor (ListT m) where-    fmap f = mapListT $ fmap $ map f--instance (Foldable f) => Foldable (ListT f) where-    foldMap f (ListT a) = foldMap (foldMap f) a--instance (Traversable f) => Traversable (ListT f) where-    traverse f (ListT a) = ListT <$> traverse (traverse f) a--instance (Applicative m) => Applicative (ListT m) where-    pure a  = ListT $ pure [a]-    f <*> v = ListT $ (<*>) <$> runListT f <*> runListT v--instance (Applicative m) => Alternative (ListT m) where-    empty   = ListT $ pure []-    m <|> n = ListT $ (++) <$> runListT m <*> runListT n--instance (Monad m) => Monad (ListT m) where-#if !(MIN_VERSION_base(4,8,0))-    return a = ListT $ return [a]-#endif-    m >>= k  = ListT $ do-        a <- runListT m-        b <- mapM (runListT . k) a-        return (concat b)-    fail _ = ListT $ return []--#if MIN_VERSION_base(4,9,0)-instance (Monad m) => Fail.MonadFail (ListT m) where-    fail _ = ListT $ return []-#endif--instance (Monad m) => MonadPlus (ListT m) where-    mzero       = ListT $ return []-    m `mplus` n = ListT $ do-        a <- runListT m-        b <- runListT n-        return (a ++ b)--instance MonadTrans ListT where-    lift m = ListT $ do-        a <- m-        return [a]--instance (MonadIO m) => MonadIO (ListT m) where-    liftIO = lift . liftIO--#if MIN_VERSION_base(4,4,0)-instance (MonadZip m) => MonadZip (ListT m) where-    mzipWith f (ListT a) (ListT b) = ListT $ mzipWith (zipWith f) a b-#endif---- | Lift a @callCC@ operation to the new monad.-liftCallCC :: CallCC m [a] [b] -> CallCC (ListT m) a b-liftCallCC callCC f = ListT $-    callCC $ \ c ->-    runListT (f (\ a -> ListT $ c [a]))---- | Lift a @catchE@ operation to the new monad.-liftCatch :: Catch e m [a] -> Catch e (ListT m) a-liftCatch catchE m h = ListT $ runListT m-    `catchE` \ e -> runListT (h e)
Control/Monad/Trans/Maybe.hs view
@@ -1,8 +1,9 @@ {-# LANGUAGE CPP #-} #if __GLASGOW_HASKELL__ >= 702 {-# LANGUAGE Safe #-}+{-# LANGUAGE DeriveGeneric #-} #endif-#if __GLASGOW_HASKELL__ >= 710+#if __GLASGOW_HASKELL__ >= 710 && __GLASGOW_HASKELL__ < 802 {-# LANGUAGE AutoDeriveTypeable #-} #endif -----------------------------------------------------------------------------@@ -30,7 +31,8 @@     -- * The MaybeT monad transformer     MaybeT(..),     mapMaybeT,-    -- * Conversion+    -- * Monad transformations+    hoistMaybe,     maybeToExceptT,     exceptToMaybeT,     -- * Lifting other operations@@ -45,6 +47,9 @@ import Control.Monad.Trans.Class import Control.Monad.Trans.Except (ExceptT(..)) import Data.Functor.Classes+#if MIN_VERSION_base(4,12,0)+import Data.Functor.Contravariant+#endif  import Control.Applicative import Control.Monad (MonadPlus(mzero, mplus), liftM)@@ -55,12 +60,17 @@ #if MIN_VERSION_base(4,4,0) import Control.Monad.Zip (MonadZip(mzipWith)) #endif-import Data.Foldable (Foldable(foldMap)) import Data.Maybe (fromMaybe)+#if !(MIN_VERSION_base(4,8,0)) || defined(__MHS__)+import Data.Foldable (Foldable(foldMap)) import Data.Traversable (Traversable(traverse))+#endif+#if __GLASGOW_HASKELL__ >= 704+import GHC.Generics+#endif --- | The parameterizable maybe monad, obtained by composing an arbitrary--- monad with the 'Maybe' monad.+-- | The parameterizable maybe monad, a strict monad obtained by composing+-- an arbitrary monad with the 'Maybe' monad. -- -- Computations are actions that may produce a value or exit. --@@ -68,12 +78,19 @@ -- value, while @>>=@ sequences two subcomputations, exiting if either -- computation does. newtype MaybeT m a = MaybeT { runMaybeT :: m (Maybe a) }+#if __GLASGOW_HASKELL__ >= 710+    deriving (Generic, Generic1)+#elif __GLASGOW_HASKELL__ >= 704+    deriving (Generic)+#endif  instance (Eq1 m) => Eq1 (MaybeT m) where     liftEq eq (MaybeT x) (MaybeT y) = liftEq (liftEq eq) x y+    {-# INLINE liftEq #-}  instance (Ord1 m) => Ord1 (MaybeT m) where     liftCompare comp (MaybeT x) (MaybeT y) = liftCompare (liftCompare comp) x y+    {-# INLINE liftCompare #-}  instance (Read1 m) => Read1 (MaybeT m) where     liftReadsPrec rp rl = readsData $@@ -99,28 +116,39 @@ -- * @'runMaybeT' ('mapMaybeT' f m) = f ('runMaybeT' m)@ mapMaybeT :: (m (Maybe a) -> n (Maybe b)) -> MaybeT m a -> MaybeT n b mapMaybeT f = MaybeT . f . runMaybeT+{-# INLINE mapMaybeT #-} +-- | Convert a 'Maybe' computation to 'MaybeT'.+hoistMaybe :: (Applicative m) => Maybe b -> MaybeT m b+hoistMaybe = MaybeT . pure+ -- | Convert a 'MaybeT' computation to 'ExceptT', with a default -- exception value. maybeToExceptT :: (Functor m) => e -> MaybeT m a -> ExceptT e m a maybeToExceptT e (MaybeT m) = ExceptT $ fmap (maybe (Left e) Right) m+{-# INLINE maybeToExceptT #-}  -- | Convert a 'ExceptT' computation to 'MaybeT', discarding the -- value of any exception. exceptToMaybeT :: (Functor m) => ExceptT e m a -> MaybeT m a exceptToMaybeT (ExceptT m) = MaybeT $ fmap (either (const Nothing) Just) m+{-# INLINE exceptToMaybeT #-}  instance (Functor m) => Functor (MaybeT m) where     fmap f = mapMaybeT (fmap (fmap f))+    {-# INLINE fmap #-}  instance (Foldable f) => Foldable (MaybeT f) where     foldMap f (MaybeT a) = foldMap (foldMap f) a+    {-# INLINE foldMap #-}  instance (Traversable f) => Traversable (MaybeT f) where     traverse f (MaybeT a) = MaybeT <$> traverse (traverse f) a+    {-# INLINE traverse #-}  instance (Functor m, Monad m) => Applicative (MaybeT m) where-    pure = lift . return+    pure = MaybeT . return . Just+    {-# INLINE pure #-}     mf <*> mx = MaybeT $ do         mb_f <- runMaybeT mf         case mb_f of@@ -130,68 +158,94 @@                 case mb_x of                     Nothing -> return Nothing                     Just x  -> return (Just (f x))+    {-# INLINE (<*>) #-}+    m *> k = m >>= \_ -> k+    {-# INLINE (*>) #-}  instance (Functor m, Monad m) => Alternative (MaybeT m) where     empty = MaybeT (return Nothing)+    {-# INLINE empty #-}     x <|> y = MaybeT $ do         v <- runMaybeT x         case v of             Nothing -> runMaybeT y             Just _  -> return v+    {-# INLINE (<|>) #-}  instance (Monad m) => Monad (MaybeT m) where #if !(MIN_VERSION_base(4,8,0))-    return = lift . return+    return = MaybeT . return . Just+    {-# INLINE return #-} #endif     x >>= f = MaybeT $ do         v <- runMaybeT x         case v of             Nothing -> return Nothing             Just y  -> runMaybeT (f y)+    {-# INLINE (>>=) #-}+#if !(MIN_VERSION_base(4,13,0))     fail _ = MaybeT (return Nothing)+    {-# INLINE fail #-}+#endif  #if MIN_VERSION_base(4,9,0) instance (Monad m) => Fail.MonadFail (MaybeT m) where     fail _ = MaybeT (return Nothing)+    {-# INLINE fail #-} #endif  instance (Monad m) => MonadPlus (MaybeT m) where     mzero = MaybeT (return Nothing)+    {-# INLINE mzero #-}     mplus x y = MaybeT $ do         v <- runMaybeT x         case v of             Nothing -> runMaybeT y             Just _  -> return v+    {-# INLINE mplus #-}  instance (MonadFix m) => MonadFix (MaybeT m) where     mfix f = MaybeT (mfix (runMaybeT . f . fromMaybe bomb))       where bomb = error "mfix (MaybeT): inner computation returned Nothing"+    {-# INLINE mfix #-}  instance MonadTrans MaybeT where     lift = MaybeT . liftM Just+    {-# INLINE lift #-}  instance (MonadIO m) => MonadIO (MaybeT m) where     liftIO = lift . liftIO+    {-# INLINE liftIO #-}  #if MIN_VERSION_base(4,4,0) instance (MonadZip m) => MonadZip (MaybeT m) where     mzipWith f (MaybeT a) (MaybeT b) = MaybeT $ mzipWith (liftA2 f) a b+    {-# INLINE mzipWith #-} #endif +#if MIN_VERSION_base(4,12,0)+instance Contravariant m => Contravariant (MaybeT m) where+    contramap f = MaybeT . contramap (fmap f) . runMaybeT+    {-# INLINE contramap #-}+#endif+ -- | Lift a @callCC@ operation to the new monad. liftCallCC :: CallCC m (Maybe a) (Maybe b) -> CallCC (MaybeT m) a b liftCallCC callCC f =     MaybeT $ callCC $ \ c -> runMaybeT (f (MaybeT . c . Just))+{-# INLINE liftCallCC #-}  -- | Lift a @catchE@ operation to the new monad. liftCatch :: Catch e m (Maybe a) -> Catch e (MaybeT m) a liftCatch f m h = MaybeT $ f (runMaybeT m) (runMaybeT . h)+{-# INLINE liftCatch #-}  -- | Lift a @listen@ operation to the new monad. liftListen :: (Monad m) => Listen w m (Maybe a) -> Listen w (MaybeT m) a liftListen listen = mapMaybeT $ \ m -> do     (a, w) <- listen m     return $! fmap (\ r -> (r, w)) a+{-# INLINE liftListen #-}  -- | Lift a @pass@ operation to the new monad. liftPass :: (Monad m) => Pass w m (Maybe a) -> Pass w (MaybeT m) a@@ -200,3 +254,4 @@     return $! case a of         Nothing     -> (Nothing, id)         Just (v, f) -> (Just v, f)+{-# INLINE liftPass #-}
Control/Monad/Trans/RWS.hs view
@@ -13,9 +13,11 @@ -- Stability   :  experimental -- Portability :  portable ----- A monad transformer that combines 'ReaderT', 'WriterT' and 'StateT'.--- This version is lazy; for a strict version, see--- "Control.Monad.Trans.RWS.Strict", which has the same interface.+-- A monad transformer that combines 'Control.Monad.Trans.Reader.ReaderT',+-- 'Control.Monad.Trans.Writer.Lazy.WriterT' and+-- 'Control.Monad.Trans.State.Lazy.StateT'.+-- This version is lazy; for a constant-space version with almost the+-- same interface, see "Control.Monad.Trans.RWS.CPS". -----------------------------------------------------------------------------  module Control.Monad.Trans.RWS (
+ Control/Monad/Trans/RWS/CPS.hs view
@@ -0,0 +1,418 @@+{-# LANGUAGE CPP #-}+#if __GLASGOW_HASKELL__ >= 702+{-# LANGUAGE Safe #-}+{-# LANGUAGE DeriveGeneric #-}+#endif+#if __GLASGOW_HASKELL__ >= 710 && __GLASGOW_HASKELL__ < 802+{-# LANGUAGE AutoDeriveTypeable #-}+#endif+-----------------------------------------------------------------------------+-- |+-- Module      :  Control.Monad.Trans.RWS.CPS+-- Copyright   :  (c) Daniel Mendler 2016,+--                (c) Andy Gill 2001,+--                (c) Oregon Graduate Institute of Science and Technology, 2001+-- License     :  BSD-style (see the file LICENSE)+--+-- Maintainer  :  R.Paterson@city.ac.uk+-- Stability   :  experimental+-- Portability :  portable+--+-- A monad transformer that combines 'Control.Monad.Trans.Reader.ReaderT',+-- 'Control.Monad.Trans.Writer.CPS.WriterT' and+-- 'Control.Monad.Trans.State.Strict.StateT'.+-- This version uses continuation-passing-style for the writer part+-- to achieve constant space usage.+-- For a lazy version with the same interface,+-- see "Control.Monad.Trans.RWS.Lazy".+-----------------------------------------------------------------------------++module Control.Monad.Trans.RWS.CPS (+    -- * The RWS monad+    RWS,+    rws,+    runRWS,+    evalRWS,+    execRWS,+    mapRWS,+    withRWS,+    -- * The RWST monad transformer+    RWST,+    rwsT,+    runRWST,+    evalRWST,+    execRWST,+    mapRWST,+    withRWST,+    -- * Reader operations+    reader,+    ask,+    local,+    asks,+    -- * Writer operations+    writer,+    tell,+    listen,+    listens,+    pass,+    censor,+    -- * State operations+    state,+    get,+    put,+    modify,+    gets,+    -- * Lifting other operations+    liftCallCC,+    liftCallCC',+    liftCatch,+  ) where++import Control.Applicative+import Control.Monad+import Control.Monad.Fix+import Control.Monad.IO.Class+import Control.Monad.Trans.Class+import Control.Monad.Signatures+import Data.Functor.Identity++#if !(MIN_VERSION_base(4,8,0))+import Data.Monoid+#endif++#if MIN_VERSION_base(4,9,0)+import qualified Control.Monad.Fail as Fail+#endif+#if __GLASGOW_HASKELL__ >= 704+import GHC.Generics+#endif++-- | A monad containing an environment of type @r@, output of type @w@+-- and an updatable state of type @s@.+type RWS r w s = RWST r w s Identity++-- | Construct an RWS computation from a function.+-- (The inverse of 'runRWS'.)+rws :: (Monoid w) => (r -> s -> (a, s, w)) -> RWS r w s a+rws f = RWST $ \ r s w ->+    let (a, s', w') = f r s; wt = w `mappend` w' in wt `seq` return (a, s', wt)+{-# INLINE rws #-}++-- | Unwrap an RWS computation as a function.+-- (The inverse of 'rws'.)+runRWS :: (Monoid w) => RWS r w s a -> r -> s -> (a, s, w)+runRWS m r s = runIdentity (runRWST m r s)+{-# INLINE runRWS #-}++-- | Evaluate a computation with the given initial state and environment,+-- returning the final value and output, discarding the final state.+evalRWS :: (Monoid w)+        => RWS r w s a  -- ^RWS computation to execute+        -> r            -- ^initial environment+        -> s            -- ^initial value+        -> (a, w)       -- ^final value and output+evalRWS m r s = let+    (a, _, w) = runRWS m r s+    in (a, w)+{-# INLINE evalRWS #-}++-- | Evaluate a computation with the given initial state and environment,+-- returning the final state and output, discarding the final value.+execRWS :: (Monoid w)+        => RWS r w s a  -- ^RWS computation to execute+        -> r            -- ^initial environment+        -> s            -- ^initial value+        -> (s, w)       -- ^final state and output+execRWS m r s = let+    (_, s', w) = runRWS m r s+    in (s', w)+{-# INLINE execRWS #-}++-- | Map the return value, final state and output of a computation using+-- the given function.+--+-- * @'runRWS' ('mapRWS' f m) r s = f ('runRWS' m r s)@+mapRWS :: (Monoid w, Monoid w') => ((a, s, w) -> (b, s, w')) -> RWS r w s a -> RWS r w' s b+mapRWS f = mapRWST (Identity . f . runIdentity)+{-# INLINE mapRWS #-}++-- | @'withRWS' f m@ executes action @m@ with an initial environment+-- and state modified by applying @f@.+--+-- * @'runRWS' ('withRWS' f m) r s = 'uncurry' ('runRWS' m) (f r s)@+withRWS :: (r' -> s -> (r, s)) -> RWS r w s a -> RWS r' w s a+withRWS = withRWST+{-# INLINE withRWS #-}++-- ---------------------------------------------------------------------------+-- | A monad transformer adding reading an environment of type @r@,+-- collecting an output of type @w@ and updating a state of type @s@+-- to an inner monad @m@.+newtype RWST r w s m a = RWST { unRWST :: r -> s -> w -> m (a, s, w) }+#if __GLASGOW_HASKELL__ >= 704+    deriving (Generic)+#endif++-- | Construct an RWST computation from a function.+-- (The inverse of 'runRWST'.)+rwsT :: (Functor m, Monoid w) => (r -> s -> m (a, s, w)) -> RWST r w s m a+rwsT f = RWST $ \ r s w ->+     (\ (a, s', w') -> let wt = w `mappend` w' in wt `seq` (a, s', wt)) <$> f r s+{-# INLINE rwsT #-}++-- | Unwrap an RWST computation as a function.+-- (The inverse of 'rwsT'.)+runRWST :: (Monoid w) => RWST r w s m a -> r -> s -> m (a, s, w)+runRWST m r s = unRWST m r s mempty+{-# INLINE runRWST #-}++-- | Evaluate a computation with the given initial state and environment,+-- returning the final value and output, discarding the final state.+evalRWST :: (Monad m, Monoid w)+         => RWST r w s m a      -- ^computation to execute+         -> r                   -- ^initial environment+         -> s                   -- ^initial value+         -> m (a, w)            -- ^computation yielding final value and output+evalRWST m r s = do+    (a, _, w) <- runRWST m r s+    return (a, w)+{-# INLINE evalRWST #-}++-- | Evaluate a computation with the given initial state and environment,+-- returning the final state and output, discarding the final value.+execRWST :: (Monad m, Monoid w)+         => RWST r w s m a      -- ^computation to execute+         -> r                   -- ^initial environment+         -> s                   -- ^initial value+         -> m (s, w)            -- ^computation yielding final state and output+execRWST m r s = do+    (_, s', w) <- runRWST m r s+    return (s', w)+{-# INLINE execRWST #-}++-- | Map the inner computation using the given function.+--+-- * @'runRWST' ('mapRWST' f m) r s = f ('runRWST' m r s)@+--mapRWST :: (m (a, s, w) -> n (b, s, w')) -> RWST r w s m a -> RWST r w' s n b+mapRWST :: (Monad n, Monoid w, Monoid w') =>+    (m (a, s, w) -> n (b, s, w')) -> RWST r w s m a -> RWST r w' s n b+mapRWST f m = RWST $ \ r s w -> do+    (a, s', w') <- f (runRWST m r s)+    let wt = w `mappend` w'+    wt `seq` return (a, s', wt)+{-# INLINE mapRWST #-}++-- | @'withRWST' f m@ executes action @m@ with an initial environment+-- and state modified by applying @f@.+--+-- * @'runRWST' ('withRWST' f m) r s = 'uncurry' ('runRWST' m) (f r s)@+withRWST :: (r' -> s -> (r, s)) -> RWST r w s m a -> RWST r' w s m a+withRWST f m = RWST $ \ r s -> uncurry (unRWST m) (f r s)+{-# INLINE withRWST #-}++instance (Functor m) => Functor (RWST r w s m) where+    fmap f m = RWST $ \ r s w -> (\ (a, s', w') -> (f a, s', w')) <$> unRWST m r s w+    {-# INLINE fmap #-}++instance (Functor m, Monad m) => Applicative (RWST r w s m) where+    pure a = RWST $ \ _ s w -> return (a, s, w)+    {-# INLINE pure #-}++    RWST mf <*> RWST mx = RWST $ \ r s w -> do+        (f, s', w')    <- mf r s w+        (x, s'', w'') <- mx r s' w'+        return (f x, s'', w'')+    {-# INLINE (<*>) #-}++instance (Functor m, MonadPlus m) => Alternative (RWST r w s m) where+    empty = RWST $ \ _ _ _ -> mzero+    {-# INLINE empty #-}++    RWST m <|> RWST n = RWST $ \ r s w -> m r s w `mplus` n r s w+    {-# INLINE (<|>) #-}++instance (Monad m) => Monad (RWST r w s m) where+#if !(MIN_VERSION_base(4,8,0))+    return a = RWST $ \ _ s w -> return (a, s, w)+    {-# INLINE return #-}+#endif++    m >>= k = RWST $ \ r s w -> do+        (a, s', w')    <- unRWST m r s w+        unRWST (k a) r s' w'+    {-# INLINE (>>=) #-}++#if !(MIN_VERSION_base(4,13,0))+    fail msg = RWST $ \ _ _ _ -> fail msg+    {-# INLINE fail #-}+#endif++#if MIN_VERSION_base(4,9,0)+instance (Fail.MonadFail m) => Fail.MonadFail (RWST r w s m) where+    fail msg = RWST $ \ _ _ _ -> Fail.fail msg+    {-# INLINE fail #-}+#endif++instance (Functor m, MonadPlus m) => MonadPlus (RWST r w s m) where+    mzero = empty+    {-# INLINE mzero #-}+    mplus = (<|>)+    {-# INLINE mplus #-}++instance (MonadFix m) => MonadFix (RWST r w s m) where+    mfix f = RWST $ \ r s w -> mfix $ \ ~(a, _, _) -> unRWST (f a) r s w+    {-# INLINE mfix #-}++instance MonadTrans (RWST r w s) where+    lift m = RWST $ \ _ s w -> do+        a <- m+        return (a, s, w)+    {-# INLINE lift #-}++instance (MonadIO m) => MonadIO (RWST r w s m) where+    liftIO = lift . liftIO+    {-# INLINE liftIO #-}+-- ---------------------------------------------------------------------------+-- Reader operations++-- | Constructor for computations in the reader monad (equivalent to 'asks').+reader :: (Monad m) => (r -> a) -> RWST r w s m a+reader = asks+{-# INLINE reader #-}++-- | Fetch the value of the environment.+ask :: (Monad m) => RWST r w s m r+ask = asks id+{-# INLINE ask #-}++-- | Execute a computation in a modified environment+--+-- * @'runRWST' ('local' f m) r s = 'runRWST' m (f r) s@+local :: (r -> r) -> RWST r w s m a -> RWST r w s m a+local f m = RWST $ \ r s w -> unRWST m (f r) s w+{-# INLINE local #-}++-- | Retrieve a function of the current environment.+--+-- * @'asks' f = 'liftM' f 'ask'@+asks :: (Monad m) => (r -> a) -> RWST r w s m a+asks f = RWST $ \ r s w -> return (f r, s, w)+{-# INLINE asks #-}++-- ---------------------------------------------------------------------------+-- Writer operations++-- | Construct a writer computation from a (result, output) pair.+writer :: (Monoid w, Monad m) => (a, w) -> RWST r w s m a+writer (a, w') = RWST $ \ _ s w -> let wt = w `mappend` w' in wt `seq` return (a, s, wt)+{-# INLINE writer #-}++-- | @'tell' w@ is an action that produces the output @w@.+tell :: (Monoid w, Monad m) => w -> RWST r w s m ()+tell w' = writer ((), w')+{-# INLINE tell #-}++-- | @'listen' m@ is an action that executes the action @m@ and adds its+-- output to the value of the computation.+--+-- * @'runRWST' ('listen' m) r s = 'liftM' (\\ (a, w) -> ((a, w), w)) ('runRWST' m r s)@+listen :: (Monoid w, Monad m) => RWST r w s m a -> RWST r w s m (a, w)+listen = listens id+{-# INLINE listen #-}++-- | @'listens' f m@ is an action that executes the action @m@ and adds+-- the result of applying @f@ to the output to the value of the computation.+--+-- * @'listens' f m = 'liftM' (id *** f) ('listen' m)@+--+-- * @'runRWST' ('listens' f m) r s = 'liftM' (\\ (a, w) -> ((a, f w), w)) ('runRWST' m r s)@+listens :: (Monoid w, Monad m) => (w -> b) -> RWST r w s m a -> RWST r w s m (a, b)+listens f m = RWST $ \ r s w -> do+    (a, s', w') <- runRWST m r s+    let wt = w `mappend` w'+    wt `seq` return ((a, f w'), s', wt)+{-# INLINE listens #-}++-- | @'pass' m@ is an action that executes the action @m@, which returns+-- a value and a function, and returns the value, applying the function+-- to the output.+--+-- * @'runRWST' ('pass' m) r s = 'liftM' (\\ ((a, f), w) -> (a, f w)) ('runRWST' m r s)@+pass :: (Monoid w, Monoid w', Monad m) => RWST r w s m (a, w -> w') -> RWST r w' s m a+pass m = RWST $ \ r s w -> do+    ((a, f), s', w') <- runRWST m r s+    let wt = w `mappend` f w'+    wt `seq` return (a, s', wt)+{-# INLINE pass #-}++-- | @'censor' f m@ is an action that executes the action @m@ and+-- applies the function @f@ to its output, leaving the return value+-- unchanged.+--+-- * @'censor' f m = 'pass' ('liftM' (\\ x -> (x,f)) m)@+--+-- * @'runRWST' ('censor' f m) r s = 'liftM' (\\ (a, w) -> (a, f w)) ('runRWST' m r s)@+censor :: (Monoid w, Monad m) => (w -> w) -> RWST r w s m a -> RWST r w s m a+censor f m = RWST $ \ r s w -> do+    (a, s', w') <- runRWST m r s+    let wt = w `mappend` f w'+    wt `seq` return (a, s', wt)+{-# INLINE censor #-}++-- ---------------------------------------------------------------------------+-- State operations++-- | Construct a state monad computation from a state transformer function.+state :: (Monad m) => (s -> (a, s)) -> RWST r w s m a+state f = RWST $ \ _ s w -> let (a, s') = f s in return (a, s', w)+{-# INLINE state #-}++-- | Fetch the current value of the state within the monad.+get :: (Monad m) =>RWST r w s m s+get = gets id+{-# INLINE get #-}++-- | @'put' s@ sets the state within the monad to @s@.+put :: (Monad m) =>s -> RWST r w s m ()+put s = RWST $ \ _ _ w -> return ((), s, w)+{-# INLINE put #-}++-- | @'modify' f@ is an action that updates the state to the result of+-- applying @f@ to the current state.+--+-- * @'modify' f = 'get' >>= ('put' . f)@+modify :: (Monad m) =>(s -> s) -> RWST r w s m ()+modify f = RWST $ \ _ s w -> return ((), f s, w)+{-# INLINE modify #-}++-- | Get a specific component of the state, using a projection function+-- supplied.+--+-- * @'gets' f = 'liftM' f 'get'@+gets :: (Monad m) =>(s -> a) -> RWST r w s m a+gets f = RWST $ \ _ s w -> return (f s, s, w)+{-# INLINE gets #-}++-- | Uniform lifting of a @callCC@ operation to the new monad.+-- This version rolls back to the original state on entering the+-- continuation.+liftCallCC :: CallCC m (a,s,w) (b,s,w) -> CallCC (RWST r w s m) a b+liftCallCC callCC f = RWST $ \ r s w ->+    callCC $ \ c -> unRWST (f (\ a -> RWST $ \ _ _ _ -> c (a, s, w))) r s w+{-# INLINE liftCallCC #-}++-- | In-situ lifting of a @callCC@ operation to the new monad.+-- This version uses the current state on entering the continuation.+liftCallCC' :: CallCC m (a,s,w) (b,s,w) -> CallCC (RWST r w s m) a b+liftCallCC' callCC f = RWST $ \ r s w ->+    callCC $ \ c -> unRWST (f (\ a -> RWST $ \ _ s' _ -> c (a, s', w))) r s w+{-# INLINE liftCallCC' #-}++-- | Lift a @catchE@ operation to the new monad.+-- The uniformity property (see "Control.Monad.Signatures") implies that+-- the lifted @catchE@ discards any output or changes to the state from+-- the body on entering the handler.+liftCatch :: Catch e m (a,s,w) -> Catch e (RWST r w s m) a+liftCatch catchE m h =+    RWST $ \ r s w -> unRWST m r s w `catchE` \ e -> unRWST (h e) r s w+{-# INLINE liftCatch #-}
Control/Monad/Trans/RWS/Lazy.hs view
@@ -1,8 +1,9 @@ {-# LANGUAGE CPP #-} #if __GLASGOW_HASKELL__ >= 702 {-# LANGUAGE Safe #-}+{-# LANGUAGE DeriveGeneric #-} #endif-#if __GLASGOW_HASKELL__ >= 710+#if __GLASGOW_HASKELL__ >= 710 && __GLASGOW_HASKELL__ < 802 {-# LANGUAGE AutoDeriveTypeable #-} #endif -----------------------------------------------------------------------------@@ -16,9 +17,11 @@ -- Stability   :  experimental -- Portability :  portable ----- A monad transformer that combines 'ReaderT', 'WriterT' and 'StateT'.--- This version is lazy; for a strict version with the same interface,--- see "Control.Monad.Trans.RWS.Strict".+-- A monad transformer that combines 'Control.Monad.Trans.Reader.ReaderT',+-- 'Control.Monad.Trans.Writer.Lazy.WriterT' and+-- 'Control.Monad.Trans.State.Lazy.StateT'.+-- This version is lazy; for a constant-space version with almost the+-- same interface, see "Control.Monad.Trans.RWS.CPS". -----------------------------------------------------------------------------  module Control.Monad.Trans.RWS.Lazy (@@ -63,6 +66,9 @@ import Control.Monad.IO.Class import Control.Monad.Signatures import Control.Monad.Trans.Class+#if MIN_VERSION_base(4,12,0)+import Data.Functor.Contravariant+#endif import Data.Functor.Identity  import Control.Applicative@@ -71,7 +77,12 @@ import qualified Control.Monad.Fail as Fail #endif import Control.Monad.Fix+#if !(MIN_VERSION_base(4,8,0)) import Data.Monoid+#endif+#if __GLASGOW_HASKELL__ >= 704+import GHC.Generics+#endif  -- | A monad containing an environment of type @r@, output of type @w@ -- and an updatable state of type @s@.@@ -81,11 +92,13 @@ -- (The inverse of 'runRWS'.) rws :: (r -> s -> (a, s, w)) -> RWS r w s a rws f = RWST (\ r s -> Identity (f r s))+{-# INLINE rws #-}  -- | Unwrap an RWS computation as a function. -- (The inverse of 'rws'.) runRWS :: RWS r w s a -> r -> s -> (a, s, w) runRWS m r s = runIdentity (runRWST m r s)+{-# INLINE runRWS #-}  -- | Evaluate a computation with the given initial state and environment, -- returning the final value and output, discarding the final state.@@ -96,6 +109,7 @@ evalRWS m r s = let     (a, _, w) = runRWS m r s     in (a, w)+{-# INLINE evalRWS #-}  -- | Evaluate a computation with the given initial state and environment, -- returning the final state and output, discarding the final value.@@ -106,6 +120,7 @@ execRWS m r s = let     (_, s', w) = runRWS m r s     in (s', w)+{-# INLINE execRWS #-}  -- | Map the return value, final state and output of a computation using -- the given function.@@ -113,6 +128,7 @@ -- * @'runRWS' ('mapRWS' f m) r s = f ('runRWS' m r s)@ mapRWS :: ((a, s, w) -> (b, s, w')) -> RWS r w s a -> RWS r w' s b mapRWS f = mapRWST (Identity . f . runIdentity)+{-# INLINE mapRWS #-}  -- | @'withRWS' f m@ executes action @m@ with an initial environment -- and state modified by applying @f@.@@ -120,13 +136,16 @@ -- * @'runRWS' ('withRWS' f m) r s = 'uncurry' ('runRWS' m) (f r s)@ withRWS :: (r' -> s -> (r, s)) -> RWS r w s a -> RWS r' w s a withRWS = withRWST+{-# INLINE withRWS #-}  -- --------------------------------------------------------------------------- -- | A monad transformer adding reading an environment of type @r@, -- collecting an output of type @w@ and updating a state of type @s@ -- to an inner monad @m@. newtype RWST r w s m a = RWST { runRWST :: r -> s -> m (a, s, w) }-+#if __GLASGOW_HASKELL__ >= 704+    deriving (Generic)+#endif -- | Evaluate a computation with the given initial state and environment, -- returning the final value and output, discarding the final state. evalRWST :: (Monad m)@@ -137,6 +156,7 @@ evalRWST m r s = do     ~(a, _, w) <- runRWST m r s     return (a, w)+{-# INLINE evalRWST #-}  -- | Evaluate a computation with the given initial state and environment, -- returning the final state and output, discarding the final value.@@ -148,12 +168,14 @@ execRWST m r s = do     ~(_, s', w) <- runRWST m r s     return (s', w)+{-# INLINE execRWST #-}  -- | Map the inner computation using the given function. -- -- * @'runRWST' ('mapRWST' f m) r s = f ('runRWST' m r s)@ mapRWST :: (m (a, s, w) -> n (b, s, w')) -> RWST r w s m a -> RWST r w' s n b mapRWST f m = RWST $ \ r s -> f (runRWST m r s)+{-# INLINE mapRWST #-}  -- | @'withRWST' f m@ executes action @m@ with an initial environment -- and state modified by applying @f@.@@ -161,74 +183,102 @@ -- * @'runRWST' ('withRWST' f m) r s = 'uncurry' ('runRWST' m) (f r s)@ withRWST :: (r' -> s -> (r, s)) -> RWST r w s m a -> RWST r' w s m a withRWST f m = RWST $ \ r s -> uncurry (runRWST m) (f r s)+{-# INLINE withRWST #-}  instance (Functor m) => Functor (RWST r w s m) where     fmap f m = RWST $ \ r s ->         fmap (\ ~(a, s', w) -> (f a, s', w)) $ runRWST m r s+    {-# INLINE fmap #-}  instance (Monoid w, Functor m, Monad m) => Applicative (RWST r w s m) where     pure a = RWST $ \ _ s -> return (a, s, mempty)+    {-# INLINE pure #-}     RWST mf <*> RWST mx  = RWST $ \ r s -> do         ~(f, s', w)  <- mf r s         ~(x, s'',w') <- mx r s'         return (f x, s'', w `mappend` w')+    {-# INLINE (<*>) #-}  instance (Monoid w, Functor m, MonadPlus m) => Alternative (RWST r w s m) where     empty = RWST $ \ _ _ -> mzero+    {-# INLINE empty #-}     RWST m <|> RWST n = RWST $ \ r s -> m r s `mplus` n r s+    {-# INLINE (<|>) #-}  instance (Monoid w, Monad m) => Monad (RWST r w s m) where #if !(MIN_VERSION_base(4,8,0))     return a = RWST $ \ _ s -> return (a, s, mempty)+    {-# INLINE return #-} #endif     m >>= k  = RWST $ \ r s -> do         ~(a, s', w)  <- runRWST m r s         ~(b, s'',w') <- runRWST (k a) r s'         return (b, s'', w `mappend` w')+    {-# INLINE (>>=) #-}+#if !(MIN_VERSION_base(4,13,0))     fail msg = RWST $ \ _ _ -> fail msg+    {-# INLINE fail #-}+#endif  #if MIN_VERSION_base(4,9,0) instance (Monoid w, Fail.MonadFail m) => Fail.MonadFail (RWST r w s m) where     fail msg = RWST $ \ _ _ -> Fail.fail msg+    {-# INLINE fail #-} #endif  instance (Monoid w, MonadPlus m) => MonadPlus (RWST r w s m) where     mzero = RWST $ \ _ _ -> mzero+    {-# INLINE mzero #-}     RWST m `mplus` RWST n = RWST $ \ r s -> m r s `mplus` n r s+    {-# INLINE mplus #-}  instance (Monoid w, MonadFix m) => MonadFix (RWST r w s m) where     mfix f = RWST $ \ r s -> mfix $ \ ~(a, _, _) -> runRWST (f a) r s+    {-# INLINE mfix #-}  instance (Monoid w) => MonadTrans (RWST r w s) where     lift m = RWST $ \ _ s -> do         a <- m         return (a, s, mempty)+    {-# INLINE lift #-}  instance (Monoid w, MonadIO m) => MonadIO (RWST r w s m) where     liftIO = lift . liftIO+    {-# INLINE liftIO #-} +#if MIN_VERSION_base(4,12,0)+instance Contravariant m => Contravariant (RWST r w s m) where+    contramap f m = RWST $ \r s ->+      contramap (\ ~(a, s', w) -> (f a, s', w)) $ runRWST m r s+    {-# INLINE contramap #-}+#endif+ -- --------------------------------------------------------------------------- -- Reader operations  -- | Constructor for computations in the reader monad (equivalent to 'asks'). reader :: (Monoid w, Monad m) => (r -> a) -> RWST r w s m a reader = asks+{-# INLINE reader #-}  -- | Fetch the value of the environment. ask :: (Monoid w, Monad m) => RWST r w s m r ask = RWST $ \ r s -> return (r, s, mempty)+{-# INLINE ask #-}  -- | Execute a computation in a modified environment -- -- * @'runRWST' ('local' f m) r s = 'runRWST' m (f r) s@ local :: (r -> r) -> RWST r w s m a -> RWST r w s m a local f m = RWST $ \ r s -> runRWST m (f r) s+{-# INLINE local #-}  -- | Retrieve a function of the current environment. -- -- * @'asks' f = 'liftM' f 'ask'@ asks :: (Monoid w, Monad m) => (r -> a) -> RWST r w s m a asks f = RWST $ \ r s -> return (f r, s, mempty)+{-# INLINE asks #-}  -- --------------------------------------------------------------------------- -- Writer operations@@ -236,10 +286,12 @@ -- | Construct a writer computation from a (result, output) pair. writer :: (Monad m) => (a, w) -> RWST r w s m a writer (a, w) = RWST $ \ _ s -> return (a, s, w)+{-# INLINE writer #-}  -- | @'tell' w@ is an action that produces the output @w@. tell :: (Monad m) => w -> RWST r w s m () tell w = RWST $ \ _ s -> return ((),s,w)+{-# INLINE tell #-}  -- | @'listen' m@ is an action that executes the action @m@ and adds its -- output to the value of the computation.@@ -249,6 +301,7 @@ listen m = RWST $ \ r s -> do     ~(a, s', w) <- runRWST m r s     return ((a, w), s', w)+{-# INLINE listen #-}  -- | @'listens' f m@ is an action that executes the action @m@ and adds -- the result of applying @f@ to the output to the value of the computation.@@ -260,6 +313,7 @@ listens f m = RWST $ \ r s -> do     ~(a, s', w) <- runRWST m r s     return ((a, f w), s', w)+{-# INLINE listens #-}  -- | @'pass' m@ is an action that executes the action @m@, which returns -- a value and a function, and returns the value, applying the function@@ -270,6 +324,7 @@ pass m = RWST $ \ r s -> do     ~((a, f), s', w) <- runRWST m r s     return (a, s', f w)+{-# INLINE pass #-}  -- | @'censor' f m@ is an action that executes the action @m@ and -- applies the function @f@ to its output, leaving the return value@@ -282,6 +337,7 @@ censor f m = RWST $ \ r s -> do     ~(a, s', w) <- runRWST m r s     return (a, s', f w)+{-# INLINE censor #-}  -- --------------------------------------------------------------------------- -- State operations@@ -289,14 +345,17 @@ -- | Construct a state monad computation from a state transformer function. state :: (Monoid w, Monad m) => (s -> (a,s)) -> RWST r w s m a state f = RWST $ \ _ s -> let (a,s') = f s  in  return (a, s', mempty)+{-# INLINE state #-}  -- | Fetch the current value of the state within the monad. get :: (Monoid w, Monad m) => RWST r w s m s get = RWST $ \ _ s -> return (s, s, mempty)+{-# INLINE get #-}  -- | @'put' s@ sets the state within the monad to @s@. put :: (Monoid w, Monad m) => s -> RWST r w s m () put s = RWST $ \ _ _ -> return ((), s, mempty)+{-# INLINE put #-}  -- | @'modify' f@ is an action that updates the state to the result of -- applying @f@ to the current state.@@ -304,6 +363,7 @@ -- * @'modify' f = 'get' >>= ('put' . f)@ modify :: (Monoid w, Monad m) => (s -> s) -> RWST r w s m () modify f = RWST $ \ _ s -> return ((), f s, mempty)+{-# INLINE modify #-}  -- | Get a specific component of the state, using a projection function -- supplied.@@ -311,6 +371,7 @@ -- * @'gets' f = 'liftM' f 'get'@ gets :: (Monoid w, Monad m) => (s -> a) -> RWST r w s m a gets f = RWST $ \ _ s -> return (f s, s, mempty)+{-# INLINE gets #-}  -- | Uniform lifting of a @callCC@ operation to the new monad. -- This version rolls back to the original state on entering the@@ -320,6 +381,7 @@ liftCallCC callCC f = RWST $ \ r s ->     callCC $ \ c ->     runRWST (f (\ a -> RWST $ \ _ _ -> c (a, s, mempty))) r s+{-# INLINE liftCallCC #-}  -- | In-situ lifting of a @callCC@ operation to the new monad. -- This version uses the current state on entering the continuation.@@ -328,8 +390,13 @@ liftCallCC' callCC f = RWST $ \ r s ->     callCC $ \ c ->     runRWST (f (\ a -> RWST $ \ _ s' -> c (a, s', mempty))) r s+{-# INLINE liftCallCC' #-}  -- | Lift a @catchE@ operation to the new monad.+-- The uniformity property (see "Control.Monad.Signatures") implies that+-- the lifted @catchE@ discards any output or changes to the state from+-- the body on entering the handler. liftCatch :: Catch e m (a,s,w) -> Catch e (RWST r w s m) a liftCatch catchE m h =     RWST $ \ r s -> runRWST m r s `catchE` \ e -> runRWST (h e) r s+{-# INLINE liftCatch #-}
Control/Monad/Trans/RWS/Strict.hs view
@@ -1,8 +1,9 @@ {-# LANGUAGE CPP #-} #if __GLASGOW_HASKELL__ >= 702 {-# LANGUAGE Safe #-}+{-# LANGUAGE DeriveGeneric #-} #endif-#if __GLASGOW_HASKELL__ >= 710+#if __GLASGOW_HASKELL__ >= 710 && __GLASGOW_HASKELL__ < 802 {-# LANGUAGE AutoDeriveTypeable #-} #endif -----------------------------------------------------------------------------@@ -16,9 +17,14 @@ -- Stability   :  experimental -- Portability :  portable ----- A monad transformer that combines 'ReaderT', 'WriterT' and 'StateT'.+-- A monad transformer that combines 'Control.Monad.Trans.Reader.ReaderT',+-- 'Control.Monad.Trans.Writer.Strict.WriterT' and+-- 'Control.Monad.Trans.State.Strict.StateT'. -- This version is strict; for a lazy version with the same interface, -- see "Control.Monad.Trans.RWS.Lazy".+-- Although the output is built strictly, it is not possible to+-- achieve constant space behaviour with this transformer: for that,+-- use "Control.Monad.Trans.RWS.CPS" instead. -----------------------------------------------------------------------------  module Control.Monad.Trans.RWS.Strict (@@ -63,6 +69,9 @@ import Control.Monad.IO.Class import Control.Monad.Signatures import Control.Monad.Trans.Class+#if MIN_VERSION_base(4,12,0)+import Data.Functor.Contravariant+#endif import Data.Functor.Identity  import Control.Applicative@@ -71,7 +80,12 @@ import qualified Control.Monad.Fail as Fail #endif import Control.Monad.Fix+#if !(MIN_VERSION_base(4,8,0)) import Data.Monoid+#endif+#if __GLASGOW_HASKELL__ >= 704+import GHC.Generics+#endif  -- | A monad containing an environment of type @r@, output of type @w@ -- and an updatable state of type @s@.@@ -81,11 +95,13 @@ -- (The inverse of 'runRWS'.) rws :: (r -> s -> (a, s, w)) -> RWS r w s a rws f = RWST (\ r s -> Identity (f r s))+{-# INLINE rws #-}  -- | Unwrap an RWS computation as a function. -- (The inverse of 'rws'.) runRWS :: RWS r w s a -> r -> s -> (a, s, w) runRWS m r s = runIdentity (runRWST m r s)+{-# INLINE runRWS #-}  -- | Evaluate a computation with the given initial state and environment, -- returning the final value and output, discarding the final state.@@ -96,6 +112,7 @@ evalRWS m r s = let     (a, _, w) = runRWS m r s     in (a, w)+{-# INLINE evalRWS #-}  -- | Evaluate a computation with the given initial state and environment, -- returning the final state and output, discarding the final value.@@ -106,6 +123,7 @@ execRWS m r s = let     (_, s', w) = runRWS m r s     in (s', w)+{-# INLINE execRWS #-}  -- | Map the return value, final state and output of a computation using -- the given function.@@ -113,6 +131,7 @@ -- * @'runRWS' ('mapRWS' f m) r s = f ('runRWS' m r s)@ mapRWS :: ((a, s, w) -> (b, s, w')) -> RWS r w s a -> RWS r w' s b mapRWS f = mapRWST (Identity . f . runIdentity)+{-# INLINE mapRWS #-}  -- | @'withRWS' f m@ executes action @m@ with an initial environment -- and state modified by applying @f@.@@ -120,12 +139,16 @@ -- * @'runRWS' ('withRWS' f m) r s = 'uncurry' ('runRWS' m) (f r s)@ withRWS :: (r' -> s -> (r, s)) -> RWS r w s a -> RWS r' w s a withRWS = withRWST+{-# INLINE withRWS #-}  -- --------------------------------------------------------------------------- -- | A monad transformer adding reading an environment of type @r@, -- collecting an output of type @w@ and updating a state of type @s@ -- to an inner monad @m@. newtype RWST r w s m a = RWST { runRWST :: r -> s -> m (a, s, w) }+#if __GLASGOW_HASKELL__ >= 704+    deriving (Generic)+#endif  -- | Evaluate a computation with the given initial state and environment, -- returning the final value and output, discarding the final state.@@ -137,6 +160,7 @@ evalRWST m r s = do     (a, _, w) <- runRWST m r s     return (a, w)+{-# INLINE evalRWST #-}  -- | Evaluate a computation with the given initial state and environment, -- returning the final state and output, discarding the final value.@@ -148,12 +172,14 @@ execRWST m r s = do     (_, s', w) <- runRWST m r s     return (s', w)+{-# INLINE execRWST #-}  -- | Map the inner computation using the given function. -- -- * @'runRWST' ('mapRWST' f m) r s = f ('runRWST' m r s)@ mapRWST :: (m (a, s, w) -> n (b, s, w')) -> RWST r w s m a -> RWST r w' s n b mapRWST f m = RWST $ \ r s -> f (runRWST m r s)+{-# INLINE mapRWST #-}  -- | @'withRWST' f m@ executes action @m@ with an initial environment -- and state modified by applying @f@.@@ -161,74 +187,102 @@ -- * @'runRWST' ('withRWST' f m) r s = 'uncurry' ('runRWST' m) (f r s)@ withRWST :: (r' -> s -> (r, s)) -> RWST r w s m a -> RWST r' w s m a withRWST f m = RWST $ \ r s -> uncurry (runRWST m) (f r s)+{-# INLINE withRWST #-}  instance (Functor m) => Functor (RWST r w s m) where     fmap f m = RWST $ \ r s ->         fmap (\ (a, s', w) -> (f a, s', w)) $ runRWST m r s+    {-# INLINE fmap #-}  instance (Monoid w, Functor m, Monad m) => Applicative (RWST r w s m) where     pure a = RWST $ \ _ s -> return (a, s, mempty)+    {-# INLINE pure #-}     RWST mf <*> RWST mx = RWST $ \ r s -> do         (f, s', w)  <- mf r s         (x, s'',w') <- mx r s'         return (f x, s'', w `mappend` w')+    {-# INLINE (<*>) #-}  instance (Monoid w, Functor m, MonadPlus m) => Alternative (RWST r w s m) where     empty = RWST $ \ _ _ -> mzero+    {-# INLINE empty #-}     RWST m <|> RWST n = RWST $ \ r s -> m r s `mplus` n r s+    {-# INLINE (<|>) #-}  instance (Monoid w, Monad m) => Monad (RWST r w s m) where #if !(MIN_VERSION_base(4,8,0))     return a = RWST $ \ _ s -> return (a, s, mempty)+    {-# INLINE return #-} #endif     m >>= k  = RWST $ \ r s -> do         (a, s', w)  <- runRWST m r s         (b, s'',w') <- runRWST (k a) r s'         return (b, s'', w `mappend` w')+    {-# INLINE (>>=) #-}+#if !(MIN_VERSION_base(4,13,0))     fail msg = RWST $ \ _ _ -> fail msg+    {-# INLINE fail #-}+#endif  #if MIN_VERSION_base(4,9,0) instance (Monoid w, Fail.MonadFail m) => Fail.MonadFail (RWST r w s m) where     fail msg = RWST $ \ _ _ -> Fail.fail msg+    {-# INLINE fail #-} #endif  instance (Monoid w, MonadPlus m) => MonadPlus (RWST r w s m) where     mzero = RWST $ \ _ _ -> mzero+    {-# INLINE mzero #-}     RWST m `mplus` RWST n = RWST $ \ r s -> m r s `mplus` n r s+    {-# INLINE mplus #-}  instance (Monoid w, MonadFix m) => MonadFix (RWST r w s m) where     mfix f = RWST $ \ r s -> mfix $ \ ~(a, _, _) -> runRWST (f a) r s+    {-# INLINE mfix #-}  instance (Monoid w) => MonadTrans (RWST r w s) where     lift m = RWST $ \ _ s -> do         a <- m         return (a, s, mempty)+    {-# INLINE lift #-}  instance (Monoid w, MonadIO m) => MonadIO (RWST r w s m) where     liftIO = lift . liftIO+    {-# INLINE liftIO #-} +#if MIN_VERSION_base(4,12,0)+instance Contravariant m => Contravariant (RWST r w s m) where+    contramap f m = RWST $ \r s ->+      contramap (\ (a, s', w) -> (f a, s', w)) $ runRWST m r s+    {-# INLINE contramap #-}+#endif+ -- --------------------------------------------------------------------------- -- Reader operations  -- | Constructor for computations in the reader monad (equivalent to 'asks'). reader :: (Monoid w, Monad m) => (r -> a) -> RWST r w s m a reader = asks+{-# INLINE reader #-}  -- | Fetch the value of the environment. ask :: (Monoid w, Monad m) => RWST r w s m r ask = RWST $ \ r s -> return (r, s, mempty)+{-# INLINE ask #-}  -- | Execute a computation in a modified environment -- -- * @'runRWST' ('local' f m) r s = 'runRWST' m (f r) s@ local :: (r -> r) -> RWST r w s m a -> RWST r w s m a local f m = RWST $ \ r s -> runRWST m (f r) s+{-# INLINE local #-}  -- | Retrieve a function of the current environment. -- -- * @'asks' f = 'liftM' f 'ask'@ asks :: (Monoid w, Monad m) => (r -> a) -> RWST r w s m a asks f = RWST $ \ r s -> return (f r, s, mempty)+{-# INLINE asks #-}  -- --------------------------------------------------------------------------- -- Writer operations@@ -236,10 +290,12 @@ -- | Construct a writer computation from a (result, output) pair. writer :: (Monad m) => (a, w) -> RWST r w s m a writer (a, w) = RWST $ \ _ s -> return (a, s, w)+{-# INLINE writer #-}  -- | @'tell' w@ is an action that produces the output @w@. tell :: (Monad m) => w -> RWST r w s m () tell w = RWST $ \ _ s -> return ((),s,w)+{-# INLINE tell #-}  -- | @'listen' m@ is an action that executes the action @m@ and adds its -- output to the value of the computation.@@ -249,6 +305,7 @@ listen m = RWST $ \ r s -> do     (a, s', w) <- runRWST m r s     return ((a, w), s', w)+{-# INLINE listen #-}  -- | @'listens' f m@ is an action that executes the action @m@ and adds -- the result of applying @f@ to the output to the value of the computation.@@ -260,6 +317,7 @@ listens f m = RWST $ \ r s -> do     (a, s', w) <- runRWST m r s     return ((a, f w), s', w)+{-# INLINE listens #-}  -- | @'pass' m@ is an action that executes the action @m@, which returns -- a value and a function, and returns the value, applying the function@@ -270,6 +328,7 @@ pass m = RWST $ \ r s -> do     ((a, f), s', w) <- runRWST m r s     return (a, s', f w)+{-# INLINE pass #-}  -- | @'censor' f m@ is an action that executes the action @m@ and -- applies the function @f@ to its output, leaving the return value@@ -282,6 +341,7 @@ censor f m = RWST $ \ r s -> do     (a, s', w) <- runRWST m r s     return (a, s', f w)+{-# INLINE censor #-}  -- --------------------------------------------------------------------------- -- State operations@@ -289,14 +349,17 @@ -- | Construct a state monad computation from a state transformer function. state :: (Monoid w, Monad m) => (s -> (a,s)) -> RWST r w s m a state f = RWST $ \ _ s -> case f s of (a,s') -> return (a, s', mempty)+{-# INLINE state #-}  -- | Fetch the current value of the state within the monad. get :: (Monoid w, Monad m) => RWST r w s m s get = RWST $ \ _ s -> return (s, s, mempty)+{-# INLINE get #-}  -- | @'put' s@ sets the state within the monad to @s@. put :: (Monoid w, Monad m) => s -> RWST r w s m () put s = RWST $ \ _ _ -> return ((), s, mempty)+{-# INLINE put #-}  -- | @'modify' f@ is an action that updates the state to the result of -- applying @f@ to the current state.@@ -304,6 +367,7 @@ -- * @'modify' f = 'get' >>= ('put' . f)@ modify :: (Monoid w, Monad m) => (s -> s) -> RWST r w s m () modify f = RWST $ \ _ s -> return ((), f s, mempty)+{-# INLINE modify #-}  -- | Get a specific component of the state, using a projection function -- supplied.@@ -311,6 +375,7 @@ -- * @'gets' f = 'liftM' f 'get'@ gets :: (Monoid w, Monad m) => (s -> a) -> RWST r w s m a gets f = RWST $ \ _ s -> return (f s, s, mempty)+{-# INLINE gets #-}  -- | Uniform lifting of a @callCC@ operation to the new monad. -- This version rolls back to the original state on entering the@@ -320,6 +385,7 @@ liftCallCC callCC f = RWST $ \ r s ->     callCC $ \ c ->     runRWST (f (\ a -> RWST $ \ _ _ -> c (a, s, mempty))) r s+{-# INLINE liftCallCC #-}  -- | In-situ lifting of a @callCC@ operation to the new monad. -- This version uses the current state on entering the continuation.@@ -328,8 +394,13 @@ liftCallCC' callCC f = RWST $ \ r s ->     callCC $ \ c ->     runRWST (f (\ a -> RWST $ \ _ s' -> c (a, s', mempty))) r s+{-# INLINE liftCallCC' #-}  -- | Lift a @catchE@ operation to the new monad.+-- The uniformity property (see "Control.Monad.Signatures") implies that+-- the lifted @catchE@ discards any output or changes to the state from+-- the body on entering the handler. liftCatch :: Catch e m (a,s,w) -> Catch e (RWST r w s m) a liftCatch catchE m h =     RWST $ \ r s -> runRWST m r s `catchE` \ e -> runRWST (h e) r s+{-# INLINE liftCatch #-}
Control/Monad/Trans/Reader.hs view
@@ -1,11 +1,9 @@ {-# LANGUAGE CPP #-} #if __GLASGOW_HASKELL__ >= 702 {-# LANGUAGE Safe #-}-#endif-#if __GLASGOW_HASKELL__ >= 704-{-# LANGUAGE PolyKinds #-}+{-# LANGUAGE DeriveGeneric #-} #endif-#if __GLASGOW_HASKELL__ >= 710+#if __GLASGOW_HASKELL__ >= 710 && __GLASGOW_HASKELL__ < 802 {-# LANGUAGE AutoDeriveTypeable #-} #endif -----------------------------------------------------------------------------@@ -49,6 +47,9 @@ import Control.Monad.IO.Class import Control.Monad.Signatures import Control.Monad.Trans.Class+#if MIN_VERSION_base(4,12,0)+import Data.Functor.Contravariant+#endif import Data.Functor.Identity  import Control.Applicative@@ -63,32 +64,44 @@ #if MIN_VERSION_base(4,4,0) import Control.Monad.Zip (MonadZip(mzipWith)) #endif+#if (MIN_VERSION_base(4,2,0)) && !(MIN_VERSION_base(4,8,0))+import Data.Functor ((<$))+#endif+#if __GLASGOW_HASKELL__ >= 704+import GHC.Generics+#endif --- | The parameterizable reader monad.+-- | The parameterizable reader monad, which is non-strict. -- -- Computations are functions of a shared environment. ----- The 'return' function ignores the environment, while @>>=@ passes--- the inherited environment to both subcomputations.+-- The 'return' function ignores the environment, while @m '>>=' k@+-- passes the inherited environment to both subcomputations:+--+-- <<images/bind-ReaderT.svg>>+-- type Reader r = ReaderT r Identity  -- | Constructor for computations in the reader monad (equivalent to 'asks'). reader :: (Monad m) => (r -> a) -> ReaderT r m a reader f = ReaderT (return . f)+{-# INLINE reader #-}  -- | Runs a @Reader@ and extracts the final value from it. -- (The inverse of 'reader'.) runReader-     :: Reader r a      -- ^ A @Reader@ to run.+    :: Reader r a       -- ^ A @Reader@ to run.     -> r                -- ^ An initial environment.     -> a runReader m = runIdentity . runReaderT m+{-# INLINE runReader #-}  -- | Transform the value returned by a @Reader@. -- -- * @'runReader' ('mapReader' f m) = f . 'runReader' m@ mapReader :: (a -> b) -> Reader r a -> Reader r b mapReader f = mapReaderT (Identity . f . runIdentity)+{-# INLINE mapReader #-}  -- | Execute a computation in a modified environment -- (a specialization of 'withReaderT').@@ -99,19 +112,31 @@     -> Reader r a       -- ^ Computation to run in the modified environment.     -> Reader r' a withReader = withReaderT+{-# INLINE withReader #-}  -- | The reader monad transformer, -- which adds a read-only environment to the given monad. ----- The 'return' function ignores the environment, while @>>=@ passes--- the inherited environment to both subcomputations.+-- The 'return' function ignores the environment, while @m '>>=' k@+-- passes the inherited environment to both subcomputations:+--+-- <<images/bind-ReaderT.svg>>+--+--+-- @ReaderT r m@ is strict if and only if @m@ is. newtype ReaderT r m a = ReaderT { runReaderT :: r -> m a }+#if __GLASGOW_HASKELL__ >= 710+    deriving (Generic, Generic1)+#elif __GLASGOW_HASKELL__ >= 704+    deriving (Generic)+#endif  -- | Transform the computation inside a @ReaderT@. -- -- * @'runReaderT' ('mapReaderT' f m) = f . 'runReaderT' m@ mapReaderT :: (m a -> n b) -> ReaderT r m a -> ReaderT r n b mapReaderT f m = ReaderT $ f . runReaderT m+{-# INLINE mapReaderT #-}  -- | Execute a computation in a modified environment -- (a more general version of 'local').@@ -122,57 +147,103 @@     -> ReaderT r m a    -- ^ Computation to run in the modified environment.     -> ReaderT r' m a withReaderT f m = ReaderT $ runReaderT m . f+{-# INLINE withReaderT #-}  instance (Functor m) => Functor (ReaderT r m) where     fmap f  = mapReaderT (fmap f)+    {-# INLINE fmap #-}+#if MIN_VERSION_base(4,2,0)+    x <$ v = mapReaderT (x <$) v+    {-# INLINE (<$) #-}+#endif  instance (Applicative m) => Applicative (ReaderT r m) where     pure    = liftReaderT . pure+    {-# INLINE pure #-}     f <*> v = ReaderT $ \ r -> runReaderT f r <*> runReaderT v r+    {-# INLINE (<*>) #-}+#if MIN_VERSION_base(4,2,0)+    u *> v = ReaderT $ \ r -> runReaderT u r *> runReaderT v r+    {-# INLINE (*>) #-}+    u <* v = ReaderT $ \ r -> runReaderT u r <* runReaderT v r+    {-# INLINE (<*) #-}+#endif+#if MIN_VERSION_base(4,10,0)+    liftA2 f x y = ReaderT $ \ r -> liftA2 f (runReaderT x r) (runReaderT y r)+    {-# INLINE liftA2 #-}+#endif  instance (Alternative m) => Alternative (ReaderT r m) where     empty   = liftReaderT empty+    {-# INLINE empty #-}     m <|> n = ReaderT $ \ r -> runReaderT m r <|> runReaderT n r+    {-# INLINE (<|>) #-}  instance (Monad m) => Monad (ReaderT r m) where #if !(MIN_VERSION_base(4,8,0))     return   = lift . return+    {-# INLINE return #-} #endif     m >>= k  = ReaderT $ \ r -> do         a <- runReaderT m r         runReaderT (k a) r+    {-# INLINE (>>=) #-}+#if MIN_VERSION_base(4,8,0)+    (>>) = (*>)+#else+    m >> k = ReaderT $ \ r -> runReaderT m r >> runReaderT k r+#endif+    {-# INLINE (>>) #-}+#if !(MIN_VERSION_base(4,13,0))     fail msg = lift (fail msg)+    {-# INLINE fail #-}+#endif  #if MIN_VERSION_base(4,9,0) instance (Fail.MonadFail m) => Fail.MonadFail (ReaderT r m) where     fail msg = lift (Fail.fail msg)+    {-# INLINE fail #-} #endif  instance (MonadPlus m) => MonadPlus (ReaderT r m) where     mzero       = lift mzero+    {-# INLINE mzero #-}     m `mplus` n = ReaderT $ \ r -> runReaderT m r `mplus` runReaderT n r+    {-# INLINE mplus #-}  instance (MonadFix m) => MonadFix (ReaderT r m) where     mfix f = ReaderT $ \ r -> mfix $ \ a -> runReaderT (f a) r+    {-# INLINE mfix #-}  instance MonadTrans (ReaderT r) where     lift   = liftReaderT+    {-# INLINE lift #-}  instance (MonadIO m) => MonadIO (ReaderT r m) where     liftIO = lift . liftIO+    {-# INLINE liftIO #-}  #if MIN_VERSION_base(4,4,0) instance (MonadZip m) => MonadZip (ReaderT r m) where     mzipWith f (ReaderT m) (ReaderT n) = ReaderT $ \ a ->         mzipWith f (m a) (n a)+    {-# INLINE mzipWith #-} #endif +#if MIN_VERSION_base(4,12,0)+instance Contravariant m => Contravariant (ReaderT r m) where+    contramap f = ReaderT . fmap (contramap f) . runReaderT+    {-# INLINE contramap #-}+#endif+ liftReaderT :: m a -> ReaderT r m a liftReaderT m = ReaderT (const m)+{-# INLINE liftReaderT #-}  -- | Fetch the value of the environment. ask :: (Monad m) => ReaderT r m r ask = ReaderT return+{-# INLINE ask #-}  -- | Execute a computation in a modified environment -- (a specialization of 'withReaderT').@@ -183,6 +254,7 @@     -> ReaderT r m a    -- ^ Computation to run in the modified environment.     -> ReaderT r m a local = withReaderT+{-# INLINE local #-}  -- | Retrieve a function of the current environment. --@@ -191,14 +263,17 @@     => (r -> a)         -- ^ The selector function to apply to the environment.     -> ReaderT r m a asks f = ReaderT (return . f)+{-# INLINE asks #-}  -- | Lift a @callCC@ operation to the new monad. liftCallCC :: CallCC m a b -> CallCC (ReaderT r m) a b liftCallCC callCC f = ReaderT $ \ r ->     callCC $ \ c ->     runReaderT (f (ReaderT . const . c)) r+{-# INLINE liftCallCC #-}  -- | Lift a @catchE@ operation to the new monad. liftCatch :: Catch e m a -> Catch e (ReaderT r m) a liftCatch f m h =     ReaderT $ \ r -> f (runReaderT m r) (\ e -> runReaderT (h e) r)+{-# INLINE liftCatch #-}
+ Control/Monad/Trans/Select.hs view
@@ -0,0 +1,160 @@+{-# LANGUAGE CPP #-}+#if __GLASGOW_HASKELL__ >= 702+{-# LANGUAGE Safe #-}+{-# LANGUAGE DeriveGeneric #-}+#endif+#if __GLASGOW_HASKELL__ >= 706+{-# LANGUAGE PolyKinds #-}+#endif+#if __GLASGOW_HASKELL__ >= 710 && __GLASGOW_HASKELL__ < 802+{-# LANGUAGE AutoDeriveTypeable #-}+#endif+-----------------------------------------------------------------------------+-- |+-- Module      :  Control.Monad.Trans.Select+-- Copyright   :  (c) Ross Paterson 2017+-- License     :  BSD-style (see the file LICENSE)+--+-- Maintainer  :  R.Paterson@city.ac.uk+-- Stability   :  experimental+-- Portability :  portable+--+-- Selection monad transformer, modelling search algorithms.+--+-- * Martin Escardo and Paulo Oliva.+--   "Selection functions, bar recursion and backward induction",+--   /Mathematical Structures in Computer Science/ 20:2 (2010), pp. 127-168.+--   <https://www.cs.bham.ac.uk/~mhe/papers/selection-escardo-oliva.pdf>+--+-- * Jules Hedges. "Monad transformers for backtracking search".+--   In /Proceedings of MSFP 2014/. <https://arxiv.org/abs/1406.2058>+-----------------------------------------------------------------------------++module Control.Monad.Trans.Select (+    -- * The Select monad+    Select,+    select,+    runSelect,+    mapSelect,+    -- * The SelectT monad transformer+    SelectT(..),+    mapSelectT,+    -- * Monad transformation+    selectToContT,+    ) where++import Control.Monad.IO.Class+import Control.Monad.Trans.Class+import Control.Monad.Trans.Cont++import Control.Applicative+import Control.Monad+#if MIN_VERSION_base(4,9,0)+import qualified Control.Monad.Fail as Fail+#endif+import Data.Functor.Identity+#if __GLASGOW_HASKELL__ >= 704+import GHC.Generics+#endif++-- | The selection monad, which is non-strict.+type Select r = SelectT r Identity++-- | Constructor for computations in the selection monad.+select :: ((a -> r) -> a) -> Select r a+select f = SelectT $ \ k -> Identity (f (runIdentity . k))+{-# INLINE select #-}++-- | Runs a @Select@ computation with a function for evaluating answers+-- to select a particular answer.  (The inverse of 'select'.)+runSelect :: Select r a -> (a -> r) -> a+runSelect m k = runIdentity (runSelectT m (Identity . k))+{-# INLINE runSelect #-}++-- | Apply a function to transform the result of a selection computation.+--+-- * @'runSelect' ('mapSelect' f m) = f . 'runSelect' m@+mapSelect :: (a -> a) -> Select r a -> Select r a+mapSelect f = mapSelectT (Identity . f . runIdentity)+{-# INLINE mapSelect #-}++-- | Selection monad transformer.+--+-- 'SelectT' is not a functor on the category of monads, and many operations+-- cannot be lifted through it.+--+-- @SelectT r m@ is strict if and only if @m@ is.+newtype SelectT r m a = SelectT {+    -- | Runs a @SelectT@ computation with a function for evaluating+    -- answers to select a particular answer.+    runSelectT :: (a -> m r) -> m a }+#if __GLASGOW_HASKELL__ >= 704+    deriving (Generic)+#endif++-- | Apply a function to transform the result of a selection computation.+-- This has a more restricted type than the @map@ operations for other+-- monad transformers, because 'SelectT' does not define a functor in+-- the category of monads.+--+-- * @'runSelectT' ('mapSelectT' f m) = f . 'runSelectT' m@+mapSelectT :: (m a -> m a) -> SelectT r m a -> SelectT r m a+mapSelectT f m = SelectT $ f . runSelectT m+{-# INLINE mapSelectT #-}++instance (Functor m) => Functor (SelectT r m) where+    fmap f (SelectT g) = SelectT (fmap f . g . (. f))+    {-# INLINE fmap #-}++instance (Functor m, Monad m) => Applicative (SelectT r m) where+    pure = lift . return+    {-# INLINE pure #-}+    SelectT gf <*> SelectT gx = SelectT $ \ k -> do+        let h f = liftM f (gx (k . f))+        f <- gf ((>>= k) . h)+        h f+    {-# INLINE (<*>) #-}+    m *> k = m >>= \_ -> k+    {-# INLINE (*>) #-}++instance (Functor m, MonadPlus m) => Alternative (SelectT r m) where+    empty = mzero+    {-# INLINE empty #-}+    (<|>) = mplus+    {-# INLINE (<|>) #-}++instance (Monad m) => Monad (SelectT r m) where+#if !(MIN_VERSION_base(4,8,0))+    return = lift . return+    {-# INLINE return #-}+#endif+    SelectT g >>= f = SelectT $ \ k -> do+        let h x = runSelectT (f x) k+        y <- g ((>>= k) . h)+        h y+    {-# INLINE (>>=) #-}++#if MIN_VERSION_base(4,9,0)+instance (Fail.MonadFail m) => Fail.MonadFail (SelectT r m) where+    fail msg = lift (Fail.fail msg)+    {-# INLINE fail #-}+#endif++instance (MonadPlus m) => MonadPlus (SelectT r m) where+    mzero = SelectT (const mzero)+    {-# INLINE mzero #-}+    SelectT f `mplus` SelectT g = SelectT $ \ k -> f k `mplus` g k+    {-# INLINE mplus #-}++instance MonadTrans (SelectT r) where+    lift = SelectT . const+    {-# INLINE lift #-}++instance (MonadIO m) => MonadIO (SelectT r m) where+    liftIO = lift . liftIO+    {-# INLINE liftIO #-}++-- | Convert a selection computation to a continuation-passing computation.+selectToContT :: (Monad m) => SelectT r m a -> ContT r m a+selectToContT (SelectT g) = ContT $ \ k -> g k >>= k+{-# INLINE selectToContT #-}
Control/Monad/Trans/State/Lazy.hs view
@@ -1,8 +1,9 @@ {-# LANGUAGE CPP #-} #if __GLASGOW_HASKELL__ >= 702 {-# LANGUAGE Safe #-}+{-# LANGUAGE DeriveGeneric #-} #endif-#if __GLASGOW_HASKELL__ >= 710+#if __GLASGOW_HASKELL__ >= 710 && __GLASGOW_HASKELL__ < 802 {-# LANGUAGE AutoDeriveTypeable #-} #endif -----------------------------------------------------------------------------@@ -55,6 +56,7 @@     put,     modify,     modify',+    modifyM,     gets,     -- * Lifting other operations     liftCallCC,@@ -62,6 +64,9 @@     liftCatch,     liftListen,     liftPass,+    -- * Conversion to and from the strict version+    strictToLazyStateT,+    lazyToStrictStateT,     -- * Examples     -- ** State monads     -- $examples@@ -76,6 +81,10 @@ import Control.Monad.IO.Class import Control.Monad.Signatures import Control.Monad.Trans.Class+import qualified Control.Monad.Trans.State.Strict as Strict+#if MIN_VERSION_base(4,12,0)+import Data.Functor.Contravariant+#endif import Data.Functor.Identity  import Control.Applicative@@ -84,6 +93,9 @@ import qualified Control.Monad.Fail as Fail #endif import Control.Monad.Fix+#if __GLASGOW_HASKELL__ >= 704+import GHC.Generics+#endif  -- --------------------------------------------------------------------------- -- | A state monad parameterized by the type @s@ of the state to carry.@@ -99,6 +111,7 @@       => (s -> (a, s))  -- ^pure state transformer       -> StateT s m a   -- ^equivalent state-passing computation state f = StateT (return . f)+{-# INLINE state #-}  -- | Unwrap a state monad computation as a function. -- (The inverse of 'state'.)@@ -106,6 +119,7 @@          -> s           -- ^initial state          -> (a, s)      -- ^return value and final state runState m = runIdentity . runStateT m+{-# INLINE runState #-}  -- | Evaluate a state computation with the given initial state -- and return the final value, discarding the final state.@@ -115,6 +129,7 @@           -> s          -- ^initial value           -> a          -- ^return value of the state computation evalState m s = fst (runState m s)+{-# INLINE evalState #-}  -- | Evaluate a state computation with the given initial state -- and return the final state, discarding the final value.@@ -124,6 +139,7 @@           -> s          -- ^initial value           -> s          -- ^final state execState m s = snd (runState m s)+{-# INLINE execState #-}  -- | Map both the return value and final state of a computation using -- the given function.@@ -131,6 +147,7 @@ -- * @'runState' ('mapState' f m) = f . 'runState' m@ mapState :: ((a, s) -> (b, s)) -> State s a -> State s b mapState f = mapStateT (Identity . f . runIdentity)+{-# INLINE mapState #-}  -- | @'withState' f m@ executes action @m@ on a state modified by -- applying @f@.@@ -138,6 +155,7 @@ -- * @'withState' f m = 'modify' f >> m@ withState :: (s -> s) -> State s a -> State s a withState = withStateT+{-# INLINE withState #-}  -- --------------------------------------------------------------------------- -- | A state transformer monad parameterized by:@@ -150,6 +168,9 @@ -- the final state of the first computation as the initial state of -- the second. newtype StateT s m a = StateT { runStateT :: s -> m (a,s) }+#if __GLASGOW_HASKELL__ >= 704+    deriving (Generic)+#endif  -- | Evaluate a state computation with the given initial state -- and return the final value, discarding the final state.@@ -159,6 +180,7 @@ evalStateT m s = do     ~(a, _) <- runStateT m s     return a+{-# INLINE evalStateT #-}  -- | Evaluate a state computation with the given initial state -- and return the final state, discarding the final value.@@ -168,6 +190,7 @@ execStateT m s = do     ~(_, s') <- runStateT m s     return s'+{-# INLINE execStateT #-}  -- | Map both the return value and final state of a computation using -- the given function.@@ -175,6 +198,7 @@ -- * @'runStateT' ('mapStateT' f m) = f . 'runStateT' m@ mapStateT :: (m (a, s) -> n (b, s)) -> StateT s m a -> StateT s n b mapStateT f m = StateT $ f . runStateT m+{-# INLINE mapStateT #-}  -- | @'withStateT' f m@ executes action @m@ on a state modified by -- applying @f@.@@ -182,59 +206,86 @@ -- * @'withStateT' f m = 'modify' f >> m@ withStateT :: (s -> s) -> StateT s m a -> StateT s m a withStateT f m = StateT $ runStateT m . f+{-# INLINE withStateT #-}  instance (Functor m) => Functor (StateT s m) where     fmap f m = StateT $ \ s ->         fmap (\ ~(a, s') -> (f a, s')) $ runStateT m s+    {-# INLINE fmap #-}  instance (Functor m, Monad m) => Applicative (StateT s m) where     pure a = StateT $ \ s -> return (a, s)+    {-# INLINE pure #-}     StateT mf <*> StateT mx = StateT $ \ s -> do         ~(f, s') <- mf s         ~(x, s'') <- mx s'         return (f x, s'')     {-# INLINE (<*>) #-}+    m *> k = m >>= \_ -> k+    {-# INLINE (*>) #-}  instance (Functor m, MonadPlus m) => Alternative (StateT s m) where     empty = StateT $ \ _ -> mzero+    {-# INLINE empty #-}     StateT m <|> StateT n = StateT $ \ s -> m s `mplus` n s+    {-# INLINE (<|>) #-}  instance (Monad m) => Monad (StateT s m) where #if !(MIN_VERSION_base(4,8,0))     return a = StateT $ \ s -> return (a, s)+    {-# INLINE return #-} #endif     m >>= k  = StateT $ \ s -> do         ~(a, s') <- runStateT m s         runStateT (k a) s'+    {-# INLINE (>>=) #-}+#if !(MIN_VERSION_base(4,13,0))     fail str = StateT $ \ _ -> fail str+    {-# INLINE fail #-}+#endif  #if MIN_VERSION_base(4,9,0) instance (Fail.MonadFail m) => Fail.MonadFail (StateT s m) where     fail str = StateT $ \ _ -> Fail.fail str+    {-# INLINE fail #-} #endif  instance (MonadPlus m) => MonadPlus (StateT s m) where     mzero       = StateT $ \ _ -> mzero+    {-# INLINE mzero #-}     StateT m `mplus` StateT n = StateT $ \ s -> m s `mplus` n s+    {-# INLINE mplus #-}  instance (MonadFix m) => MonadFix (StateT s m) where     mfix f = StateT $ \ s -> mfix $ \ ~(a, _) -> runStateT (f a) s+    {-# INLINE mfix #-}  instance MonadTrans (StateT s) where     lift m = StateT $ \ s -> do         a <- m         return (a, s)+    {-# INLINE lift #-}  instance (MonadIO m) => MonadIO (StateT s m) where     liftIO = lift . liftIO+    {-# INLINE liftIO #-} +#if MIN_VERSION_base(4,12,0)+instance Contravariant m => Contravariant (StateT s m) where+    contramap f m = StateT $ \s ->+      contramap (\ ~(a, s') -> (f a, s')) $ runStateT m s+    {-# INLINE contramap #-}+#endif+ -- | Fetch the current value of the state within the monad. get :: (Monad m) => StateT s m s get = state $ \ s -> (s, s)+{-# INLINE get #-}  -- | @'put' s@ sets the state within the monad to @s@. put :: (Monad m) => s -> StateT s m () put s = state $ \ _ -> ((), s)+{-# INLINE put #-}  -- | @'modify' f@ is an action that updates the state to the result of -- applying @f@ to the current state.@@ -242,6 +293,7 @@ -- * @'modify' f = 'get' >>= ('put' . f)@ modify :: (Monad m) => (s -> s) -> StateT s m () modify f = state $ \ s -> ((), f s)+{-# INLINE modify #-}  -- | A variant of 'modify' in which the computation is strict in the -- new state.@@ -251,13 +303,23 @@ modify' f = do     s <- get     put $! f s+{-# INLINE modify' #-} +-- | A variant of 'modify' in which the new state is generated by a+-- monadic action.+modifyM :: (Monad m) => (s -> m s) -> StateT s m ()+modifyM f = StateT $ \ s -> do+    s' <- f s+    return ((), s')+{-# INLINE modifyM #-}+ -- | Get a specific component of the state, using a projection function -- supplied. -- -- * @'gets' f = 'liftM' f 'get'@ gets :: (Monad m) => (s -> a) -> StateT s m a gets f = state $ \ s -> (f s, s)+{-# INLINE gets #-}  -- | Uniform lifting of a @callCC@ operation to the new monad. -- This version rolls back to the original state on entering the@@ -266,6 +328,7 @@ liftCallCC callCC f = StateT $ \ s ->     callCC $ \ c ->     runStateT (f (\ a -> StateT $ \ _ -> c (a, s))) s+{-# INLINE liftCallCC #-}  -- | In-situ lifting of a @callCC@ operation to the new monad. -- This version uses the current state on entering the continuation.@@ -274,23 +337,40 @@ liftCallCC' callCC f = StateT $ \ s ->     callCC $ \ c ->     runStateT (f (\ a -> StateT $ \ s' -> c (a, s'))) s+{-# INLINE liftCallCC' #-}  -- | Lift a @catchE@ operation to the new monad.+-- The uniformity property (see "Control.Monad.Signatures") implies+-- that the lifted @catchE@ rolls back to the original state on entering+-- the handler. liftCatch :: Catch e m (a,s) -> Catch e (StateT s m) a liftCatch catchE m h =     StateT $ \ s -> runStateT m s `catchE` \ e -> runStateT (h e) s+{-# INLINE liftCatch #-}  -- | Lift a @listen@ operation to the new monad. liftListen :: (Monad m) => Listen w m (a,s) -> Listen w (StateT s m) a liftListen listen m = StateT $ \ s -> do     ~((a, s'), w) <- listen (runStateT m s)     return ((a, w), s')+{-# INLINE liftListen #-}  -- | Lift a @pass@ operation to the new monad. liftPass :: (Monad m) => Pass w m (a,s) -> Pass w (StateT s m) a liftPass pass m = StateT $ \ s -> pass $ do     ~((a, f), s') <- runStateT m s     return ((a, s'), f)+{-# INLINE liftPass #-}++-- | Convert from the strict version to the lazy version+strictToLazyStateT :: Strict.StateT s m a -> StateT s m a+strictToLazyStateT (Strict.StateT f) = StateT f+{-# INLINE strictToLazyStateT #-}++-- | Convert from the lazy version to the strict version+lazyToStrictStateT :: StateT s m a -> Strict.StateT s m a+lazyToStrictStateT (StateT f) = Strict.StateT f+{-# INLINE lazyToStrictStateT #-}  {- $examples
Control/Monad/Trans/State/Strict.hs view
@@ -1,8 +1,9 @@ {-# LANGUAGE CPP #-} #if __GLASGOW_HASKELL__ >= 702 {-# LANGUAGE Safe #-}+{-# LANGUAGE DeriveGeneric #-} #endif-#if __GLASGOW_HASKELL__ >= 710+#if __GLASGOW_HASKELL__ >= 710 && __GLASGOW_HASKELL__ < 802 {-# LANGUAGE AutoDeriveTypeable #-} #endif -----------------------------------------------------------------------------@@ -52,6 +53,7 @@     put,     modify,     modify',+    modifyM,     gets,     -- * Lifting other operations     liftCallCC,@@ -73,6 +75,9 @@ import Control.Monad.IO.Class import Control.Monad.Signatures import Control.Monad.Trans.Class+#if MIN_VERSION_base(4,12,0)+import Data.Functor.Contravariant+#endif import Data.Functor.Identity  import Control.Applicative@@ -81,6 +86,9 @@ import qualified Control.Monad.Fail as Fail #endif import Control.Monad.Fix+#if __GLASGOW_HASKELL__ >= 704+import GHC.Generics+#endif  -- --------------------------------------------------------------------------- -- | A state monad parameterized by the type @s@ of the state to carry.@@ -96,6 +104,7 @@       => (s -> (a, s))  -- ^pure state transformer       -> StateT s m a   -- ^equivalent state-passing computation state f = StateT (return . f)+{-# INLINE state #-}  -- | Unwrap a state monad computation as a function. -- (The inverse of 'state'.)@@ -103,6 +112,7 @@          -> s           -- ^initial state          -> (a, s)      -- ^return value and final state runState m = runIdentity . runStateT m+{-# INLINE runState #-}  -- | Evaluate a state computation with the given initial state -- and return the final value, discarding the final state.@@ -112,6 +122,7 @@           -> s          -- ^initial value           -> a          -- ^return value of the state computation evalState m s = fst (runState m s)+{-# INLINE evalState #-}  -- | Evaluate a state computation with the given initial state -- and return the final state, discarding the final value.@@ -121,6 +132,7 @@           -> s          -- ^initial value           -> s          -- ^final state execState m s = snd (runState m s)+{-# INLINE execState #-}  -- | Map both the return value and final state of a computation using -- the given function.@@ -128,6 +140,7 @@ -- * @'runState' ('mapState' f m) = f . 'runState' m@ mapState :: ((a, s) -> (b, s)) -> State s a -> State s b mapState f = mapStateT (Identity . f . runIdentity)+{-# INLINE mapState #-}  -- | @'withState' f m@ executes action @m@ on a state modified by -- applying @f@.@@ -135,6 +148,7 @@ -- * @'withState' f m = 'modify' f >> m@ withState :: (s -> s) -> State s a -> State s a withState = withStateT+{-# INLINE withState #-}  -- --------------------------------------------------------------------------- -- | A state transformer monad parameterized by:@@ -147,6 +161,9 @@ -- the final state of the first computation as the initial state of -- the second. newtype StateT s m a = StateT { runStateT :: s -> m (a,s) }+#if __GLASGOW_HASKELL__ >= 704+    deriving (Generic)+#endif  -- | Evaluate a state computation with the given initial state -- and return the final value, discarding the final state.@@ -156,6 +173,7 @@ evalStateT m s = do     (a, _) <- runStateT m s     return a+{-# INLINE evalStateT #-}  -- | Evaluate a state computation with the given initial state -- and return the final state, discarding the final value.@@ -165,6 +183,7 @@ execStateT m s = do     (_, s') <- runStateT m s     return s'+{-# INLINE execStateT #-}  -- | Map both the return value and final state of a computation using -- the given function.@@ -172,6 +191,7 @@ -- * @'runStateT' ('mapStateT' f m) = f . 'runStateT' m@ mapStateT :: (m (a, s) -> n (b, s)) -> StateT s m a -> StateT s n b mapStateT f m = StateT $ f . runStateT m+{-# INLINE mapStateT #-}  -- | @'withStateT' f m@ executes action @m@ on a state modified by -- applying @f@.@@ -179,59 +199,86 @@ -- * @'withStateT' f m = 'modify' f >> m@ withStateT :: (s -> s) -> StateT s m a -> StateT s m a withStateT f m = StateT $ runStateT m . f+{-# INLINE withStateT #-}  instance (Functor m) => Functor (StateT s m) where     fmap f m = StateT $ \ s ->         fmap (\ (a, s') -> (f a, s')) $ runStateT m s+    {-# INLINE fmap #-}  instance (Functor m, Monad m) => Applicative (StateT s m) where     pure a = StateT $ \ s -> return (a, s)+    {-# INLINE pure #-}     StateT mf <*> StateT mx = StateT $ \ s -> do         (f, s') <- mf s         (x, s'') <- mx s'         return (f x, s'')     {-# INLINE (<*>) #-}+    m *> k = m >>= \_ -> k+    {-# INLINE (*>) #-}  instance (Functor m, MonadPlus m) => Alternative (StateT s m) where     empty = StateT $ \ _ -> mzero+    {-# INLINE empty #-}     StateT m <|> StateT n = StateT $ \ s -> m s `mplus` n s+    {-# INLINE (<|>) #-}  instance (Monad m) => Monad (StateT s m) where #if !(MIN_VERSION_base(4,8,0))     return a = StateT $ \ s -> return (a, s)+    {-# INLINE return #-} #endif     m >>= k  = StateT $ \ s -> do         (a, s') <- runStateT m s         runStateT (k a) s'+    {-# INLINE (>>=) #-}+#if !(MIN_VERSION_base(4,13,0))     fail str = StateT $ \ _ -> fail str+    {-# INLINE fail #-}+#endif  #if MIN_VERSION_base(4,9,0) instance (Fail.MonadFail m) => Fail.MonadFail (StateT s m) where     fail str = StateT $ \ _ -> Fail.fail str+    {-# INLINE fail #-} #endif  instance (MonadPlus m) => MonadPlus (StateT s m) where     mzero       = StateT $ \ _ -> mzero-    m `mplus` n = StateT $ \ s -> runStateT m s `mplus` runStateT n s+    {-# INLINE mzero #-}+    StateT m `mplus` StateT n = StateT $ \ s -> m s `mplus` n s+    {-# INLINE mplus #-}  instance (MonadFix m) => MonadFix (StateT s m) where     mfix f = StateT $ \ s -> mfix $ \ ~(a, _) -> runStateT (f a) s+    {-# INLINE mfix #-}  instance MonadTrans (StateT s) where     lift m = StateT $ \ s -> do         a <- m         return (a, s)+    {-# INLINE lift #-}  instance (MonadIO m) => MonadIO (StateT s m) where     liftIO = lift . liftIO+    {-# INLINE liftIO #-} +#if MIN_VERSION_base(4,12,0)+instance Contravariant m => Contravariant (StateT s m) where+    contramap f m = StateT $ \s ->+      contramap (\ (a, s') -> (f a, s')) $ runStateT m s+    {-# INLINE contramap #-}+#endif+ -- | Fetch the current value of the state within the monad. get :: (Monad m) => StateT s m s get = state $ \ s -> (s, s)+{-# INLINE get #-}  -- | @'put' s@ sets the state within the monad to @s@. put :: (Monad m) => s -> StateT s m () put s = state $ \ _ -> ((), s)+{-# INLINE put #-}  -- | @'modify' f@ is an action that updates the state to the result of -- applying @f@ to the current state.@@ -239,22 +286,37 @@ -- * @'modify' f = 'get' >>= ('put' . f)@ modify :: (Monad m) => (s -> s) -> StateT s m () modify f = state $ \ s -> ((), f s)+{-# INLINE modify #-}  -- | A variant of 'modify' in which the computation is strict in the -- new state. -- -- * @'modify'' f = 'get' >>= (('$!') 'put' . f)@+--+-- Note that this is only strict in the top level of the state.+-- Lazy components of the state will not be evaluated unless @f@+-- evaluates them. modify' :: (Monad m) => (s -> s) -> StateT s m () modify' f = do     s <- get     put $! f s+{-# INLINE modify' #-} +-- | A variant of 'modify' in which the new state is generated by a+-- monadic action.+modifyM :: (Monad m) => (s -> m s) -> StateT s m ()+modifyM f = StateT $ \ s -> do+    s' <- f s+    return ((), s')+{-# INLINE modifyM #-}+ -- | Get a specific component of the state, using a projection function -- supplied. -- -- * @'gets' f = 'liftM' f 'get'@ gets :: (Monad m) => (s -> a) -> StateT s m a gets f = state $ \ s -> (f s, s)+{-# INLINE gets #-}  -- | Uniform lifting of a @callCC@ operation to the new monad. -- This version rolls back to the original state on entering the@@ -263,6 +325,7 @@ liftCallCC callCC f = StateT $ \ s ->     callCC $ \ c ->     runStateT (f (\ a -> StateT $ \ _ -> c (a, s))) s+{-# INLINE liftCallCC #-}  -- | In-situ lifting of a @callCC@ operation to the new monad. -- This version uses the current state on entering the continuation.@@ -271,23 +334,30 @@ liftCallCC' callCC f = StateT $ \ s ->     callCC $ \ c ->     runStateT (f (\ a -> StateT $ \ s' -> c (a, s'))) s+{-# INLINE liftCallCC' #-}  -- | Lift a @catchE@ operation to the new monad.+-- The uniformity property (see "Control.Monad.Signatures") implies+-- that the lifted @catchE@ rolls back to the original state on entering+-- the handler. liftCatch :: Catch e m (a,s) -> Catch e (StateT s m) a liftCatch catchE m h =     StateT $ \ s -> runStateT m s `catchE` \ e -> runStateT (h e) s+{-# INLINE liftCatch #-}  -- | Lift a @listen@ operation to the new monad. liftListen :: (Monad m) => Listen w m (a,s) -> Listen w (StateT s m) a liftListen listen m = StateT $ \ s -> do     ((a, s'), w) <- listen (runStateT m s)     return ((a, w), s')+{-# INLINE liftListen #-}  -- | Lift a @pass@ operation to the new monad. liftPass :: (Monad m) => Pass w m (a,s) -> Pass w (StateT s m) a liftPass pass m = StateT $ \ s -> pass $ do     ((a, f), s') <- runStateT m s     return ((a, s'), f)+{-# INLINE liftPass #-}  {- $examples
Control/Monad/Trans/Writer.hs view
@@ -14,8 +14,8 @@ -- Portability :  portable -- -- The WriterT monad transformer.--- This version is lazy; for a strict version, see--- "Control.Monad.Trans.Writer.Strict", which has the same interface.+-- This version builds its output lazily; for a constant-space version+-- with almost the same interface, see "Control.Monad.Trans.Writer.CPS". -----------------------------------------------------------------------------  module Control.Monad.Trans.Writer (
+ Control/Monad/Trans/Writer/CPS.hs view
@@ -0,0 +1,301 @@+{-# LANGUAGE CPP #-}+#if __GLASGOW_HASKELL__ >= 702+{-# LANGUAGE Safe #-}+{-# LANGUAGE DeriveGeneric #-}+#endif+#if __GLASGOW_HASKELL__ >= 710 && __GLASGOW_HASKELL__ < 802+{-# LANGUAGE AutoDeriveTypeable #-}+#endif+-----------------------------------------------------------------------------+-- |+-- Module      :  Control.Monad.Trans.Writer.CPS+-- Copyright   :  (c) Daniel Mendler 2016,+--                (c) Andy Gill 2001,+--                (c) Oregon Graduate Institute of Science and Technology, 2001+-- License     :  BSD-style (see the file LICENSE)+--+-- Maintainer  :  R.Paterson@city.ac.uk+-- Stability   :  experimental+-- Portability :  portable+--+-- The strict 'WriterT' monad transformer, which adds collection of+-- outputs (such as a count or string output) to a given monad.+--+-- This monad transformer provides only limited access to the output+-- during the computation. For more general access, use+-- "Control.Monad.Trans.State" instead.+--+-- This version builds its output strictly and uses continuation-passing-style+-- to achieve constant space usage. This transformer can be used as a+-- drop-in replacement for "Control.Monad.Trans.Writer.Strict".+-----------------------------------------------------------------------------++module Control.Monad.Trans.Writer.CPS (+    -- * The Writer monad+    Writer,+    writer,+    runWriter,+    execWriter,+    mapWriter,+    -- * The WriterT monad transformer+    WriterT,+    writerT,+    runWriterT,+    execWriterT,+    mapWriterT,+    -- * Writer operations+    tell,+    listen,+    listens,+    pass,+    censor,+    -- * Lifting other operations+    liftCallCC,+    liftCatch,+  ) where++import Control.Applicative+import Control.Monad+import Control.Monad.Fix+import Control.Monad.IO.Class+import Control.Monad.Trans.Class+import Control.Monad.Signatures+import Data.Functor.Identity++#if !(MIN_VERSION_base(4,8,0))+import Data.Monoid+#endif++#if MIN_VERSION_base(4,9,0)+import qualified Control.Monad.Fail as Fail+#endif+#if __GLASGOW_HASKELL__ >= 704+import GHC.Generics+#endif++-- ---------------------------------------------------------------------------+-- | A writer monad parameterized by the type @w@ of output to accumulate.+--+-- The 'return' function produces the output 'mempty', while @m '>>=' k@+-- combines the outputs of the subcomputations using 'mappend' (also+-- known as @<>@):+--+-- <<images/bind-WriterT.svg>>+--+type Writer w = WriterT w Identity++-- | Construct a writer computation from a (result, output) pair.+-- (The inverse of 'runWriter'.)+writer :: (Monoid w, Monad m) => (a, w) -> WriterT w m a+writer (a, w') = WriterT $ \ w ->+    let wt = w `mappend` w' in wt `seq` return (a, wt)+{-# INLINE writer #-}++-- | Unwrap a writer computation as a (result, output) pair.+-- (The inverse of 'writer'.)+runWriter :: (Monoid w) => Writer w a -> (a, w)+runWriter = runIdentity . runWriterT+{-# INLINE runWriter #-}++-- | Extract the output from a writer computation.+--+-- * @'execWriter' m = 'snd' ('runWriter' m)@+execWriter :: (Monoid w) => Writer w a -> w+execWriter = runIdentity . execWriterT+{-# INLINE execWriter #-}++-- | Map both the return value and output of a computation using+-- the given function.+--+-- * @'runWriter' ('mapWriter' f m) = f ('runWriter' m)@+mapWriter :: (Monoid w, Monoid w') =>+    ((a, w) -> (b, w')) -> Writer w a -> Writer w' b+mapWriter f = mapWriterT (Identity . f . runIdentity)+{-# INLINE mapWriter #-}++-- ---------------------------------------------------------------------------+-- | A writer monad parameterized by:+--+--   * @w@ - the output to accumulate.+--+--   * @m@ - The inner monad.+--+-- The 'return' function produces the output 'mempty', while @m '>>=' k@+-- combines the outputs of the subcomputations using 'mappend' (also+-- known as @<>@):+--+-- <<images/bind-WriterT.svg>>+--+newtype WriterT w m a = WriterT { unWriterT :: w -> m (a, w) }+#if __GLASGOW_HASKELL__ >= 704+    deriving (Generic)+#endif++-- | Construct a writer computation from a (result, output) computation.+-- (The inverse of 'runWriterT'.)+writerT :: (Functor m, Monoid w) => m (a, w) -> WriterT w m a+writerT f = WriterT $ \ w ->+    (\ (a, w') -> let wt = w `mappend` w' in wt `seq` (a, wt)) <$> f+{-# INLINE writerT #-}++-- | Unwrap a writer computation.+-- (The inverse of 'writerT'.)+runWriterT :: (Monoid w) => WriterT w m a -> m (a, w)+runWriterT m = unWriterT m mempty+{-# INLINE runWriterT #-}++-- | Extract the output from a writer computation.+--+-- * @'execWriterT' m = 'liftM' 'snd' ('runWriterT' m)@+execWriterT :: (Monad m, Monoid w) => WriterT w m a -> m w+execWriterT m = do+    (_, w) <- runWriterT m+    return w+{-# INLINE execWriterT #-}++-- | Map both the return value and output of a computation using+-- the given function.+--+-- * @'runWriterT' ('mapWriterT' f m) = f ('runWriterT' m)@+mapWriterT :: (Monad n, Monoid w, Monoid w') =>+    (m (a, w) -> n (b, w')) -> WriterT w m a -> WriterT w' n b+mapWriterT f m = WriterT $ \ w -> do+    (a, w') <- f (runWriterT m)+    let wt = w `mappend` w'+    wt `seq` return (a, wt)+{-# INLINE mapWriterT #-}++instance (Functor m) => Functor (WriterT w m) where+    fmap f m = WriterT $ \ w -> (\ (a, w') -> (f a, w')) <$> unWriterT m w+    {-# INLINE fmap #-}++instance (Functor m, Monad m) => Applicative (WriterT w m) where+    pure a = WriterT $ \ w -> return (a, w)+    {-# INLINE pure #-}++    WriterT mf <*> WriterT mx = WriterT $ \ w -> do+        (f, w') <- mf w+        (x, w'') <- mx w'+        return (f x, w'')+    {-# INLINE (<*>) #-}++instance (Functor m, MonadPlus m) => Alternative (WriterT w m) where+    empty = WriterT $ const mzero+    {-# INLINE empty #-}++    WriterT m <|> WriterT n = WriterT $ \ w -> m w `mplus` n w+    {-# INLINE (<|>) #-}++instance (Monad m) => Monad (WriterT w m) where+#if !(MIN_VERSION_base(4,8,0))+    return a = WriterT $ \ w -> return (a, w)+    {-# INLINE return #-}+#endif++    m >>= k = WriterT $ \ w -> do+        (a, w') <- unWriterT m w+        unWriterT (k a) w'+    {-# INLINE (>>=) #-}++#if !(MIN_VERSION_base(4,13,0))+    fail msg = WriterT $ \ _ -> fail msg+    {-# INLINE fail #-}+#endif++#if MIN_VERSION_base(4,9,0)+instance (Fail.MonadFail m) => Fail.MonadFail (WriterT w m) where+    fail msg = WriterT $ \ _ -> Fail.fail msg+    {-# INLINE fail #-}+#endif++instance (Functor m, MonadPlus m) => MonadPlus (WriterT w m) where+    mzero = empty+    {-# INLINE mzero #-}+    mplus = (<|>)+    {-# INLINE mplus #-}++instance (MonadFix m) => MonadFix (WriterT w m) where+    mfix f = WriterT $ \ w -> mfix $ \ ~(a, _) -> unWriterT (f a) w+    {-# INLINE mfix #-}++instance MonadTrans (WriterT w) where+    lift m = WriterT $ \ w -> do+        a <- m+        return (a, w)+    {-# INLINE lift #-}++instance (MonadIO m) => MonadIO (WriterT w m) where+    liftIO = lift . liftIO+    {-# INLINE liftIO #-}++-- | @'tell' w@ is an action that produces the output @w@.+tell :: (Monoid w, Monad m) => w -> WriterT w m ()+tell w = writer ((), w)+{-# INLINE tell #-}++-- | @'listen' m@ is an action that executes the action @m@ and adds its+-- output to the value of the computation.+--+-- * @'runWriterT' ('listen' m) = 'liftM' (\\ (a, w) -> ((a, w), w)) ('runWriterT' m)@+listen :: (Monoid w, Monad m) => WriterT w m a -> WriterT w m (a, w)+listen = listens id+{-# INLINE listen #-}++-- | @'listens' f m@ is an action that executes the action @m@ and adds+-- the result of applying @f@ to the output to the value of the computation.+--+-- * @'listens' f m = 'liftM' (id *** f) ('listen' m)@+--+-- * @'runWriterT' ('listens' f m) = 'liftM' (\\ (a, w) -> ((a, f w), w)) ('runWriterT' m)@+listens :: (Monoid w, Monad m) =>+    (w -> b) -> WriterT w m a -> WriterT w m (a, b)+listens f m = WriterT $ \ w -> do+    (a, w') <- runWriterT m+    let wt = w `mappend` w'+    wt `seq` return ((a, f w'), wt)+{-# INLINE listens #-}++-- | @'pass' m@ is an action that executes the action @m@, which returns+-- a value and a function, and returns the value, applying the function+-- to the output.+--+-- * @'runWriterT' ('pass' m) = 'liftM' (\\ ((a, f), w) -> (a, f w)) ('runWriterT' m)@+pass :: (Monoid w, Monoid w', Monad m) =>+    WriterT w m (a, w -> w') -> WriterT w' m a+pass m = WriterT $ \ w -> do+    ((a, f), w') <- runWriterT m+    let wt = w `mappend` f w'+    wt `seq` return (a, wt)+{-# INLINE pass #-}++-- | @'censor' f m@ is an action that executes the action @m@ and+-- applies the function @f@ to its output, leaving the return value+-- unchanged.+--+-- * @'censor' f m = 'pass' ('liftM' (\\ x -> (x,f)) m)@+--+-- * @'runWriterT' ('censor' f m) = 'liftM' (\\ (a, w) -> (a, f w)) ('runWriterT' m)@+censor :: (Monoid w, Monad m) => (w -> w) -> WriterT w m a -> WriterT w m a+censor f m = WriterT $ \ w -> do+    (a, w') <- runWriterT m+    let wt = w `mappend` f w'+    wt `seq` return (a, wt)+{-# INLINE censor #-}++-- | Uniform lifting of a @callCC@ operation to the new monad.+-- The uniformity property (see "Control.Monad.Signatures") implies that+-- the lifted @callCC@ discards any output from the body on entering+-- the saved continuation.+liftCallCC :: CallCC m (a, w) (b, w) -> CallCC (WriterT w m) a b+liftCallCC callCC f = WriterT $ \ w ->+    callCC $ \ c -> unWriterT (f (\ a -> WriterT $ \ _ -> c (a, w))) w+{-# INLINE liftCallCC #-}++-- | Lift a @catchE@ operation to the new monad.+-- The uniformity property (see "Control.Monad.Signatures") implies that+-- the lifted @catchE@ discards any output from the body on entering+-- the handler.+liftCatch :: Catch e m (a, w) -> Catch e (WriterT w m) a+liftCatch catchE m h = WriterT $ \ w ->+    unWriterT m w `catchE` \ e -> unWriterT (h e) w+{-# INLINE liftCatch #-}
Control/Monad/Trans/Writer/Lazy.hs view
@@ -1,8 +1,9 @@ {-# LANGUAGE CPP #-} #if __GLASGOW_HASKELL__ >= 702 {-# LANGUAGE Safe #-}+{-# LANGUAGE DeriveGeneric #-} #endif-#if __GLASGOW_HASKELL__ >= 710+#if __GLASGOW_HASKELL__ >= 710 && __GLASGOW_HASKELL__ < 802 {-# LANGUAGE AutoDeriveTypeable #-} #endif -----------------------------------------------------------------------------@@ -23,8 +24,8 @@ -- during the computation.  For more general access, use -- "Control.Monad.Trans.State" instead. ----- This version builds its output lazily; for a strict version with--- the same interface, see "Control.Monad.Trans.Writer.Strict".+-- This version builds its output lazily; for a constant-space version+-- with almost the same interface, see "Control.Monad.Trans.Writer.CPS". -----------------------------------------------------------------------------  module Control.Monad.Trans.Writer.Lazy (@@ -52,6 +53,9 @@ import Control.Monad.IO.Class import Control.Monad.Trans.Class import Data.Functor.Classes+#if MIN_VERSION_base(4,12,0)+import Data.Functor.Contravariant+#endif import Data.Functor.Identity  import Control.Applicative@@ -64,32 +68,45 @@ #if MIN_VERSION_base(4,4,0) import Control.Monad.Zip (MonadZip(mzipWith)) #endif-import Data.Foldable (Foldable(foldMap))+import Data.Foldable import Data.Monoid+#if !(MIN_VERSION_base(4,8,0)) || defined(__MHS__) import Data.Traversable (Traversable(traverse))+#endif+import Prelude hiding (null, length)+#if __GLASGOW_HASKELL__ >= 704+import GHC.Generics+#endif  -- --------------------------------------------------------------------------- -- | A writer monad parameterized by the type @w@ of output to accumulate. ----- The 'return' function produces the output 'mempty', while @>>=@--- combines the outputs of the subcomputations using 'mappend'.+-- The 'return' function produces the output 'mempty', while @m '>>=' k@+-- combines the outputs of the subcomputations using 'mappend' (also+-- known as @<>@):+--+-- <<images/bind-WriterT.svg>>+-- type Writer w = WriterT w Identity  -- | Construct a writer computation from a (result, output) pair. -- (The inverse of 'runWriter'.) writer :: (Monad m) => (a, w) -> WriterT w m a writer = WriterT . return+{-# INLINE writer #-}  -- | Unwrap a writer computation as a (result, output) pair. -- (The inverse of 'writer'.) runWriter :: Writer w a -> (a, w) runWriter = runIdentity . runWriterT+{-# INLINE runWriter #-}  -- | Extract the output from a writer computation. -- -- * @'execWriter' m = 'snd' ('runWriter' m)@ execWriter :: Writer w a -> w execWriter m = snd (runWriter m)+{-# INLINE execWriter #-}  -- | Map both the return value and output of a computation using -- the given function.@@ -97,6 +114,7 @@ -- * @'runWriter' ('mapWriter' f m) = f ('runWriter' m)@ mapWriter :: ((a, w) -> (b, w')) -> Writer w a -> Writer w' b mapWriter f = mapWriterT (Identity . f . runIdentity)+{-# INLINE mapWriter #-}  -- --------------------------------------------------------------------------- -- | A writer monad parameterized by:@@ -105,16 +123,25 @@ -- --   * @m@ - The inner monad. ----- The 'return' function produces the output 'mempty', while @>>=@--- combines the outputs of the subcomputations using 'mappend'.+-- The 'return' function produces the output 'mempty', while @m '>>=' k@+-- combines the outputs of the subcomputations using 'mappend' (also+-- known as @<>@):+--+-- <<images/bind-WriterT.svg>>+-- newtype WriterT w m a = WriterT { runWriterT :: m (a, w) }+#if __GLASGOW_HASKELL__ >= 704+    deriving (Generic)+#endif  instance (Eq w, Eq1 m) => Eq1 (WriterT w m) where     liftEq eq (WriterT m1) (WriterT m2) = liftEq (liftEq2 eq (==)) m1 m2+    {-# INLINE liftEq #-}  instance (Ord w, Ord1 m) => Ord1 (WriterT w m) where     liftCompare comp (WriterT m1) (WriterT m2) =         liftCompare (liftCompare2 comp compare) m1 m2+    {-# INLINE liftCompare #-}  instance (Read w, Read1 m) => Read1 (WriterT w m) where     liftReadsPrec rp rl = readsData $@@ -144,6 +171,7 @@ execWriterT m = do     ~(_, w) <- runWriterT m     return w+{-# INLINE execWriterT #-}  -- | Map both the return value and output of a computation using -- the given function.@@ -151,65 +179,96 @@ -- * @'runWriterT' ('mapWriterT' f m) = f ('runWriterT' m)@ mapWriterT :: (m (a, w) -> n (b, w')) -> WriterT w m a -> WriterT w' n b mapWriterT f m = WriterT $ f (runWriterT m)+{-# INLINE mapWriterT #-}  instance (Functor m) => Functor (WriterT w m) where     fmap f = mapWriterT $ fmap $ \ ~(a, w) -> (f a, w)+    {-# INLINE fmap #-}  instance (Foldable f) => Foldable (WriterT w f) where     foldMap f = foldMap (f . fst) . runWriterT+    {-# INLINE foldMap #-}+#if MIN_VERSION_base(4,8,0)+    null (WriterT t) = null t+    length (WriterT t) = length t+#endif  instance (Traversable f) => Traversable (WriterT w f) where     traverse f = fmap WriterT . traverse f' . runWriterT where        f' (a, b) = fmap (\ c -> (c, b)) (f a)+    {-# INLINE traverse #-}  instance (Monoid w, Applicative m) => Applicative (WriterT w m) where     pure a  = WriterT $ pure (a, mempty)+    {-# INLINE pure #-}     f <*> v = WriterT $ liftA2 k (runWriterT f) (runWriterT v)       where k ~(a, w) ~(b, w') = (a b, w `mappend` w')+    {-# INLINE (<*>) #-}  instance (Monoid w, Alternative m) => Alternative (WriterT w m) where     empty   = WriterT empty+    {-# INLINE empty #-}     m <|> n = WriterT $ runWriterT m <|> runWriterT n+    {-# INLINE (<|>) #-}  instance (Monoid w, Monad m) => Monad (WriterT w m) where #if !(MIN_VERSION_base(4,8,0))     return a = writer (a, mempty)+    {-# INLINE return #-} #endif     m >>= k  = WriterT $ do         ~(a, w)  <- runWriterT m         ~(b, w') <- runWriterT (k a)         return (b, w `mappend` w')+    {-# INLINE (>>=) #-}+#if !(MIN_VERSION_base(4,13,0))     fail msg = WriterT $ fail msg+    {-# INLINE fail #-}+#endif  #if MIN_VERSION_base(4,9,0) instance (Monoid w, Fail.MonadFail m) => Fail.MonadFail (WriterT w m) where     fail msg = WriterT $ Fail.fail msg+    {-# INLINE fail #-} #endif  instance (Monoid w, MonadPlus m) => MonadPlus (WriterT w m) where     mzero       = WriterT mzero+    {-# INLINE mzero #-}     m `mplus` n = WriterT $ runWriterT m `mplus` runWriterT n+    {-# INLINE mplus #-}  instance (Monoid w, MonadFix m) => MonadFix (WriterT w m) where     mfix m = WriterT $ mfix $ \ ~(a, _) -> runWriterT (m a)+    {-# INLINE mfix #-}  instance (Monoid w) => MonadTrans (WriterT w) where     lift m = WriterT $ do         a <- m         return (a, mempty)+    {-# INLINE lift #-}  instance (Monoid w, MonadIO m) => MonadIO (WriterT w m) where     liftIO = lift . liftIO+    {-# INLINE liftIO #-}  #if MIN_VERSION_base(4,4,0) instance (Monoid w, MonadZip m) => MonadZip (WriterT w m) where     mzipWith f (WriterT x) (WriterT y) = WriterT $         mzipWith (\ ~(a, w) ~(b, w') -> (f a b, w `mappend` w')) x y+    {-# INLINE mzipWith #-} #endif +#if MIN_VERSION_base(4,12,0)+instance Contravariant m => Contravariant (WriterT w m) where+    contramap f = mapWriterT $ contramap $ \ ~(a, w) -> (f a, w)+    {-# INLINE contramap #-}+#endif+ -- | @'tell' w@ is an action that produces the output @w@. tell :: (Monad m) => w -> WriterT w m () tell w = writer ((), w)+{-# INLINE tell #-}  -- | @'listen' m@ is an action that executes the action @m@ and adds its -- output to the value of the computation.@@ -219,6 +278,7 @@ listen m = WriterT $ do     ~(a, w) <- runWriterT m     return ((a, w), w)+{-# INLINE listen #-}  -- | @'listens' f m@ is an action that executes the action @m@ and adds -- the result of applying @f@ to the output to the value of the computation.@@ -230,6 +290,7 @@ listens f m = WriterT $ do     ~(a, w) <- runWriterT m     return ((a, f w), w)+{-# INLINE listens #-}  -- | @'pass' m@ is an action that executes the action @m@, which returns -- a value and a function, and returns the value, applying the function@@ -240,6 +301,7 @@ pass m = WriterT $ do     ~((a, f), w) <- runWriterT m     return (a, f w)+{-# INLINE pass #-}  -- | @'censor' f m@ is an action that executes the action @m@ and -- applies the function @f@ to its output, leaving the return value@@ -252,14 +314,23 @@ censor f m = WriterT $ do     ~(a, w) <- runWriterT m     return (a, f w)+{-# INLINE censor #-}  -- | Lift a @callCC@ operation to the new monad.+-- The uniformity property (see "Control.Monad.Signatures") implies that+-- the lifted @callCC@ discards any output from the body on entering+-- the saved condinuation. liftCallCC :: (Monoid w) => CallCC m (a,w) (b,w) -> CallCC (WriterT w m) a b liftCallCC callCC f = WriterT $     callCC $ \ c ->     runWriterT (f (\ a -> WriterT $ c (a, mempty)))+{-# INLINE liftCallCC #-}  -- | Lift a @catchE@ operation to the new monad.+-- The uniformity property (see "Control.Monad.Signatures") implies that+-- the lifted @catchE@ discards any output from the body on entering+-- the handler. liftCatch :: Catch e m (a,w) -> Catch e (WriterT w m) a liftCatch catchE m h =     WriterT $ runWriterT m `catchE` \ e -> runWriterT (h e)+{-# INLINE liftCatch #-}
Control/Monad/Trans/Writer/Strict.hs view
@@ -1,8 +1,9 @@ {-# LANGUAGE CPP #-} #if __GLASGOW_HASKELL__ >= 702 {-# LANGUAGE Safe #-}+{-# LANGUAGE DeriveGeneric #-} #endif-#if __GLASGOW_HASKELL__ >= 710+#if __GLASGOW_HASKELL__ >= 710 && __GLASGOW_HASKELL__ < 802 {-# LANGUAGE AutoDeriveTypeable #-} #endif -----------------------------------------------------------------------------@@ -27,7 +28,7 @@ -- the same interface, see "Control.Monad.Trans.Writer.Lazy". -- Although the output is built strictly, it is not possible to -- achieve constant space behaviour with this transformer: for that,--- use "Control.Monad.Trans.State.Strict" instead.+-- use "Control.Monad.Trans.Writer.CPS" instead. -----------------------------------------------------------------------------  module Control.Monad.Trans.Writer.Strict (@@ -55,6 +56,9 @@ import Control.Monad.IO.Class import Control.Monad.Trans.Class import Data.Functor.Classes+#if MIN_VERSION_base(4,12,0)+import Data.Functor.Contravariant+#endif import Data.Functor.Identity  import Control.Applicative@@ -67,32 +71,45 @@ #if MIN_VERSION_base(4,4,0) import Control.Monad.Zip (MonadZip(mzipWith)) #endif-import Data.Foldable (Foldable(foldMap))+import Data.Foldable import Data.Monoid+#if !(MIN_VERSION_base(4,8,0)) || defined(__MHS__) import Data.Traversable (Traversable(traverse))+#endif+import Prelude hiding (null, length)+#if __GLASGOW_HASKELL__ >= 704+import GHC.Generics+#endif  -- --------------------------------------------------------------------------- -- | A writer monad parameterized by the type @w@ of output to accumulate. ----- The 'return' function produces the output 'mempty', while @>>=@--- combines the outputs of the subcomputations using 'mappend'.+-- The 'return' function produces the output 'mempty', while @m '>>=' k@+-- combines the outputs of the subcomputations using 'mappend' (also+-- known as @<>@):+--+-- <<images/bind-WriterT.svg>>+-- type Writer w = WriterT w Identity  -- | Construct a writer computation from a (result, output) pair. -- (The inverse of 'runWriter'.) writer :: (Monad m) => (a, w) -> WriterT w m a writer = WriterT . return+{-# INLINE writer #-}  -- | Unwrap a writer computation as a (result, output) pair. -- (The inverse of 'writer'.) runWriter :: Writer w a -> (a, w) runWriter = runIdentity . runWriterT+{-# INLINE runWriter #-}  -- | Extract the output from a writer computation. -- -- * @'execWriter' m = 'snd' ('runWriter' m)@ execWriter :: Writer w a -> w execWriter m = snd (runWriter m)+{-# INLINE execWriter #-}  -- | Map both the return value and output of a computation using -- the given function.@@ -100,6 +117,7 @@ -- * @'runWriter' ('mapWriter' f m) = f ('runWriter' m)@ mapWriter :: ((a, w) -> (b, w')) -> Writer w a -> Writer w' b mapWriter f = mapWriterT (Identity . f . runIdentity)+{-# INLINE mapWriter #-}  -- --------------------------------------------------------------------------- -- | A writer monad parameterized by:@@ -108,16 +126,25 @@ -- --   * @m@ - The inner monad. ----- The 'return' function produces the output 'mempty', while @>>=@--- combines the outputs of the subcomputations using 'mappend'.+-- The 'return' function produces the output 'mempty', while @m '>>=' k@+-- combines the outputs of the subcomputations using 'mappend' (also+-- known as @<>@):+--+-- <<images/bind-WriterT.svg>>+-- newtype WriterT w m a = WriterT { runWriterT :: m (a, w) }+#if __GLASGOW_HASKELL__ >= 704+    deriving (Generic)+#endif  instance (Eq w, Eq1 m) => Eq1 (WriterT w m) where     liftEq eq (WriterT m1) (WriterT m2) = liftEq (liftEq2 eq (==)) m1 m2+    {-# INLINE liftEq #-}  instance (Ord w, Ord1 m) => Ord1 (WriterT w m) where     liftCompare comp (WriterT m1) (WriterT m2) =         liftCompare (liftCompare2 comp compare) m1 m2+    {-# INLINE liftCompare #-}  instance (Read w, Read1 m) => Read1 (WriterT w m) where     liftReadsPrec rp rl = readsData $@@ -147,6 +174,7 @@ execWriterT m = do     (_, w) <- runWriterT m     return w+{-# INLINE execWriterT #-}  -- | Map both the return value and output of a computation using -- the given function.@@ -154,65 +182,96 @@ -- * @'runWriterT' ('mapWriterT' f m) = f ('runWriterT' m)@ mapWriterT :: (m (a, w) -> n (b, w')) -> WriterT w m a -> WriterT w' n b mapWriterT f m = WriterT $ f (runWriterT m)+{-# INLINE mapWriterT #-}  instance (Functor m) => Functor (WriterT w m) where     fmap f = mapWriterT $ fmap $ \ (a, w) -> (f a, w)+    {-# INLINE fmap #-}  instance (Foldable f) => Foldable (WriterT w f) where     foldMap f = foldMap (f . fst) . runWriterT+    {-# INLINE foldMap #-}+#if MIN_VERSION_base(4,8,0)+    null (WriterT t) = null t+    length (WriterT t) = length t+#endif  instance (Traversable f) => Traversable (WriterT w f) where     traverse f = fmap WriterT . traverse f' . runWriterT where        f' (a, b) = fmap (\ c -> (c, b)) (f a)+    {-# INLINE traverse #-}  instance (Monoid w, Applicative m) => Applicative (WriterT w m) where     pure a  = WriterT $ pure (a, mempty)+    {-# INLINE pure #-}     f <*> v = WriterT $ liftA2 k (runWriterT f) (runWriterT v)       where k (a, w) (b, w') = (a b, w `mappend` w')+    {-# INLINE (<*>) #-}  instance (Monoid w, Alternative m) => Alternative (WriterT w m) where     empty   = WriterT empty+    {-# INLINE empty #-}     m <|> n = WriterT $ runWriterT m <|> runWriterT n+    {-# INLINE (<|>) #-}  instance (Monoid w, Monad m) => Monad (WriterT w m) where #if !(MIN_VERSION_base(4,8,0))     return a = writer (a, mempty)+    {-# INLINE return #-} #endif     m >>= k  = WriterT $ do         (a, w)  <- runWriterT m         (b, w') <- runWriterT (k a)         return (b, w `mappend` w')+    {-# INLINE (>>=) #-}+#if !(MIN_VERSION_base(4,13,0))     fail msg = WriterT $ fail msg+    {-# INLINE fail #-}+#endif  #if MIN_VERSION_base(4,9,0) instance (Monoid w, Fail.MonadFail m) => Fail.MonadFail (WriterT w m) where     fail msg = WriterT $ Fail.fail msg+    {-# INLINE fail #-} #endif  instance (Monoid w, MonadPlus m) => MonadPlus (WriterT w m) where     mzero       = WriterT mzero+    {-# INLINE mzero #-}     m `mplus` n = WriterT $ runWriterT m `mplus` runWriterT n+    {-# INLINE mplus #-}  instance (Monoid w, MonadFix m) => MonadFix (WriterT w m) where     mfix m = WriterT $ mfix $ \ ~(a, _) -> runWriterT (m a)+    {-# INLINE mfix #-}  instance (Monoid w) => MonadTrans (WriterT w) where     lift m = WriterT $ do         a <- m         return (a, mempty)+    {-# INLINE lift #-}  instance (Monoid w, MonadIO m) => MonadIO (WriterT w m) where     liftIO = lift . liftIO+    {-# INLINE liftIO #-}  #if MIN_VERSION_base(4,4,0) instance (Monoid w, MonadZip m) => MonadZip (WriterT w m) where     mzipWith f (WriterT x) (WriterT y) = WriterT $         mzipWith (\ (a, w) (b, w') -> (f a b, w `mappend` w')) x y+    {-# INLINE mzipWith #-} #endif +#if MIN_VERSION_base(4,12,0)+instance Contravariant m => Contravariant (WriterT w m) where+    contramap f = mapWriterT $ contramap $ \ (a, w) -> (f a, w)+    {-# INLINE contramap #-}+#endif+ -- | @'tell' w@ is an action that produces the output @w@. tell :: (Monad m) => w -> WriterT w m () tell w = writer ((), w)+{-# INLINE tell #-}  -- | @'listen' m@ is an action that executes the action @m@ and adds its -- output to the value of the computation.@@ -222,6 +281,7 @@ listen m = WriterT $ do     (a, w) <- runWriterT m     return ((a, w), w)+{-# INLINE listen #-}  -- | @'listens' f m@ is an action that executes the action @m@ and adds -- the result of applying @f@ to the output to the value of the computation.@@ -233,6 +293,7 @@ listens f m = WriterT $ do     (a, w) <- runWriterT m     return ((a, f w), w)+{-# INLINE listens #-}  -- | @'pass' m@ is an action that executes the action @m@, which returns -- a value and a function, and returns the value, applying the function@@ -243,6 +304,7 @@ pass m = WriterT $ do     ((a, f), w) <- runWriterT m     return (a, f w)+{-# INLINE pass #-}  -- | @'censor' f m@ is an action that executes the action @m@ and -- applies the function @f@ to its output, leaving the return value@@ -255,14 +317,23 @@ censor f m = WriterT $ do     (a, w) <- runWriterT m     return (a, f w)+{-# INLINE censor #-}  -- | Lift a @callCC@ operation to the new monad.+-- The uniformity property (see "Control.Monad.Signatures") implies that+-- the lifted @callCC@ discards any output from the body on entering+-- the saved continuation. liftCallCC :: (Monoid w) => CallCC m (a,w) (b,w) -> CallCC (WriterT w m) a b liftCallCC callCC f = WriterT $     callCC $ \ c ->     runWriterT (f (\ a -> WriterT $ c (a, mempty)))+{-# INLINE liftCallCC #-}  -- | Lift a @catchE@ operation to the new monad.+-- The uniformity property (see "Control.Monad.Signatures") implies that+-- the lifted @catchE@ discards any output from the body on entering+-- the handler. liftCatch :: Catch e m (a,w) -> Catch e (WriterT w m) a liftCatch catchE m h =     WriterT $ runWriterT m `catchE` \ e -> runWriterT (h e)+{-# INLINE liftCatch #-}
Data/Functor/Constant.hs view
@@ -1,11 +1,15 @@ {-# LANGUAGE CPP #-}+#if __GLASGOW_HASKELL__ >= 800+{-# LANGUAGE DeriveDataTypeable #-}+#endif #if __GLASGOW_HASKELL__ >= 702 {-# LANGUAGE Safe #-}+{-# LANGUAGE DeriveGeneric #-} #endif-#if __GLASGOW_HASKELL__ >= 704+#if __GLASGOW_HASKELL__ >= 706 {-# LANGUAGE PolyKinds #-} #endif-#if __GLASGOW_HASKELL__ >= 710+#if __GLASGOW_HASKELL__ >= 710 && __GLASGOW_HASKELL__ < 802 {-# LANGUAGE AutoDeriveTypeable #-} #endif -----------------------------------------------------------------------------@@ -26,18 +30,46 @@   ) where  import Data.Functor.Classes+#if MIN_VERSION_base(4,12,0)+import Data.Functor.Contravariant+#endif  import Control.Applicative-import Data.Foldable (Foldable(foldMap))+import Data.Foldable+#if !(MIN_VERSION_base(4,8,0)) || defined(__MHS__) import Data.Monoid (Monoid(..)) import Data.Traversable (Traversable(traverse))+#endif #if MIN_VERSION_base(4,8,0) import Data.Bifunctor (Bifunctor(..)) #endif+#if (MIN_VERSION_base(4,9,0)) && !(MIN_VERSION_base(4,11,0))+import Data.Semigroup (Semigroup((<>)))+#endif+#if MIN_VERSION_base(4,10,0)+import Data.Bifoldable (Bifoldable(..))+import Data.Bitraversable (Bitraversable(..))+#endif+import Prelude hiding (null, length)+#if __GLASGOW_HASKELL__ >= 800+import Data.Data+#endif+#if __GLASGOW_HASKELL__ >= 704+import GHC.Generics+#endif  -- | Constant functor. newtype Constant a b = Constant { getConstant :: a }-    deriving (Eq, Ord)+    deriving (Eq, Ord+#if __GLASGOW_HASKELL__ >= 800+        , Data+#endif+#if __GLASGOW_HASKELL__ >= 710+        , Generic, Generic1+#elif __GLASGOW_HASKELL__ >= 704+        , Generic+#endif+        )  -- These instances would be equivalent to the derived instances of the -- newtype if the field were removed.@@ -53,9 +85,11 @@  instance Eq2 Constant where     liftEq2 eq _ (Constant x) (Constant y) = eq x y+    {-# INLINE liftEq2 #-}  instance Ord2 Constant where     liftCompare2 comp _ (Constant x) (Constant y) = comp x y+    {-# INLINE liftCompare2 #-}  instance Read2 Constant where     liftReadsPrec2 rp _ _ _ = readsData $@@ -66,32 +100,74 @@  instance (Eq a) => Eq1 (Constant a) where     liftEq = liftEq2 (==)+    {-# INLINE liftEq #-} instance (Ord a) => Ord1 (Constant a) where     liftCompare = liftCompare2 compare+    {-# INLINE liftCompare #-} instance (Read a) => Read1 (Constant a) where     liftReadsPrec = liftReadsPrec2 readsPrec readList+    {-# INLINE liftReadsPrec #-} instance (Show a) => Show1 (Constant a) where     liftShowsPrec = liftShowsPrec2 showsPrec showList+    {-# INLINE liftShowsPrec #-}  instance Functor (Constant a) where     fmap _ (Constant x) = Constant x+    {-# INLINE fmap #-}  instance Foldable (Constant a) where     foldMap _ (Constant _) = mempty+    {-# INLINE foldMap #-}+#if MIN_VERSION_base(4,8,0)+    null (Constant _) = True+    length (Constant _) = 0+#endif  instance Traversable (Constant a) where     traverse _ (Constant x) = pure (Constant x)+    {-# INLINE traverse #-} +#if MIN_VERSION_base(4,9,0)+instance (Semigroup a) => Semigroup (Constant a b) where+    Constant x <> Constant y = Constant (x <> y)+    {-# INLINE (<>) #-}+#endif+ instance (Monoid a) => Applicative (Constant a) where     pure _ = Constant mempty+    {-# INLINE pure #-}     Constant x <*> Constant y = Constant (x `mappend` y)+    {-# INLINE (<*>) #-}  instance (Monoid a) => Monoid (Constant a b) where     mempty = Constant mempty+    {-# INLINE mempty #-}+#if !MIN_VERSION_base(4,11,0)+    -- From base-4.11, Monoid(mappend) defaults to Semigroup((<>))     Constant x `mappend` Constant y = Constant (x `mappend` y)+    {-# INLINE mappend #-}+#endif  #if MIN_VERSION_base(4,8,0) instance Bifunctor Constant where     first f (Constant x) = Constant (f x)+    {-# INLINE first #-}     second _ (Constant x) = Constant x+    {-# INLINE second #-}+#endif++#if MIN_VERSION_base(4,10,0)+instance Bifoldable Constant where+    bifoldMap f _ (Constant a) = f a+    {-# INLINE bifoldMap #-}++instance Bitraversable Constant where+    bitraverse f _ (Constant a) = Constant <$> f a+    {-# INLINE bitraverse #-}+#endif++#if MIN_VERSION_base(4,12,0)+instance Contravariant (Constant a) where+    contramap _ (Constant a) = Constant a+    {-# INLINE contramap #-} #endif
Data/Functor/Reverse.hs view
@@ -1,11 +1,12 @@ {-# LANGUAGE CPP #-} #if __GLASGOW_HASKELL__ >= 702 {-# LANGUAGE Safe #-}+{-# LANGUAGE DeriveGeneric #-} #endif-#if __GLASGOW_HASKELL__ >= 704+#if __GLASGOW_HASKELL__ >= 706 {-# LANGUAGE PolyKinds #-} #endif-#if __GLASGOW_HASKELL__ >= 710+#if __GLASGOW_HASKELL__ >= 710 && __GLASGOW_HASKELL__ < 802 {-# LANGUAGE AutoDeriveTypeable #-} #endif -----------------------------------------------------------------------------@@ -27,23 +28,45 @@   ) where  import Control.Applicative.Backwards+#if MIN_VERSION_base(4,18,0)+import Data.Foldable1 (Foldable1(foldMap1))+#endif import Data.Functor.Classes+#if MIN_VERSION_base(4,12,0)+import Data.Functor.Contravariant+#endif -import Prelude hiding (foldr, foldr1, foldl, foldl1)+import Prelude hiding (foldr, foldr1, foldl, foldl1, null, length) import Control.Applicative+import Control.Monad+#if MIN_VERSION_base(4,9,0)+import qualified Control.Monad.Fail as Fail+#endif import Data.Foldable-import Data.Traversable+#if !(MIN_VERSION_base(4,8,0)) || defined(__MHS__)+import Data.Traversable (Traversable(traverse))+#endif import Data.Monoid+#if __GLASGOW_HASKELL__ >= 704+import GHC.Generics+#endif  -- | The same functor, but with 'Foldable' and 'Traversable' instances -- that process the elements in the reverse order. newtype Reverse f a = Reverse { getReverse :: f a }+#if __GLASGOW_HASKELL__ >= 710+    deriving (Generic, Generic1)+#elif __GLASGOW_HASKELL__ >= 704+    deriving (Generic)+#endif  instance (Eq1 f) => Eq1 (Reverse f) where     liftEq eq (Reverse x) (Reverse y) = liftEq eq x y+    {-# INLINE liftEq #-}  instance (Ord1 f) => Ord1 (Reverse f) where     liftCompare comp (Reverse x) (Reverse y) = liftCompare comp x y+    {-# INLINE liftCompare #-}  instance (Read1 f) => Read1 (Reverse f) where     liftReadsPrec rp rl = readsData $@@ -61,28 +84,80 @@ -- | Derived instance. instance (Functor f) => Functor (Reverse f) where     fmap f (Reverse a) = Reverse (fmap f a)+    {-# INLINE fmap #-}  -- | Derived instance. instance (Applicative f) => Applicative (Reverse f) where     pure a = Reverse (pure a)+    {-# INLINE pure #-}     Reverse f <*> Reverse a = Reverse (f <*> a)+    {-# INLINE (<*>) #-}  -- | Derived instance. instance (Alternative f) => Alternative (Reverse f) where     empty = Reverse empty+    {-# INLINE empty #-}     Reverse x <|> Reverse y = Reverse (x <|> y)+    {-# INLINE (<|>) #-} +-- | Derived instance.+instance (Monad m) => Monad (Reverse m) where+#if !(MIN_VERSION_base(4,8,0))+    return a = Reverse (return a)+    {-# INLINE return #-}+#endif+    m >>= f = Reverse (getReverse m >>= getReverse . f)+    {-# INLINE (>>=) #-}+#if !(MIN_VERSION_base(4,13,0))+    fail msg = Reverse (fail msg)+    {-# INLINE fail #-}+#endif++#if MIN_VERSION_base(4,9,0)+instance (Fail.MonadFail m) => Fail.MonadFail (Reverse m) where+    fail msg = Reverse (Fail.fail msg)+    {-# INLINE fail #-}+#endif++-- | Derived instance.+instance (MonadPlus m) => MonadPlus (Reverse m) where+    mzero = Reverse mzero+    {-# INLINE mzero #-}+    Reverse x `mplus` Reverse y = Reverse (x `mplus` y)+    {-# INLINE mplus #-}+ -- | Fold from right to left. instance (Foldable f) => Foldable (Reverse f) where     foldMap f (Reverse t) = getDual (foldMap (Dual . f) t)+    {-# INLINE foldMap #-}     foldr f z (Reverse t) = foldl (flip f) z t+    {-# INLINE foldr #-}     foldl f z (Reverse t) = foldr (flip f) z t+    {-# INLINE foldl #-}     foldr1 f (Reverse t) = foldl1 (flip f) t+    {-# INLINE foldr1 #-}     foldl1 f (Reverse t) = foldr1 (flip f) t+    {-# INLINE foldl1 #-}+#if MIN_VERSION_base(4,8,0)+    null (Reverse t) = null t+    length (Reverse t) = length t+#endif +#if MIN_VERSION_base(4,18,0)+-- | Fold from right to left.+instance (Foldable1 f) => Foldable1 (Reverse f) where+    foldMap1 f (Reverse t) = getDual (foldMap1 (Dual . f) t)+#endif+ -- | Traverse from right to left. instance (Traversable f) => Traversable (Reverse f) where     traverse f (Reverse t) =         fmap Reverse . forwards $ traverse (Backwards . f) t-    sequenceA (Reverse t) =-        fmap Reverse . forwards $ sequenceA (fmap Backwards t)+    {-# INLINE traverse #-}++#if MIN_VERSION_base(4,12,0)+-- | Derived instance.+instance (Contravariant f) => Contravariant (Reverse f) where+    contramap f = Reverse . contramap f . getReverse+    {-# INLINE contramap #-}+#endif
changelog view
@@ -1,5 +1,101 @@ -*-change-log-*- +0.6.3.0 Ross Paterson <R.Paterson@city.ac.uk> Jan 2026+	* Add Control.Monad.Trans.Except.onE+	* Add strictToLazyState and lazyToStrictStateT++0.6.2.0 Ross Paterson <R.Paterson@city.ac.uk> Apr 2025+	* Redefine runAccumT, runExceptT and runSelectT as fields+	* Document strictness of some transformers++0.6.1.2 Ross Paterson <R.Paterson@city.ac.uk> Sep 2024+	* Portability fixes for MicroHs+	* Include image files in the bundle+	* Expand ExceptT documentation++0.6.1.1 Ross Paterson <R.Paterson@city.ac.uk> Aug 2023+	* Additions to documentation, especially of AccumT.++0.6.1.0 Ross Paterson <R.Paterson@city.ac.uk> Feb 2023+	* Add instances of Foldable1 (class added to base-4.18)+	* Add modifyM to StateT transformers++0.6.0.6 Ross Paterson <R.Paterson@city.ac.uk> Jan 2023+	* Fix for GHC 8.6++0.6.0.5 Ross Paterson <R.Paterson@city.ac.uk> Jan 2023+	* Revert to allowing MonadTrans constraint with GHC >= 8.6++0.6.0.4 Ross Paterson <R.Paterson@city.ac.uk> Feb 2022+	* Restrict deriving (Generic) to GHC >= 7.4++0.6.0.3 Ross Paterson <R.Paterson@city.ac.uk> Feb 2022+	* Restrict MonadTrans constraint to GHC >= 8.8++0.6.0.2 Ross Paterson <R.Paterson@city.ac.uk> Jul 2021+	* Further backward compatability fix++0.6.0.1 Ross Paterson <R.Paterson@city.ac.uk> Jul 2021+	* Backward compatability fixes++0.6.0.0 Ross Paterson <R.Paterson@city.ac.uk> Jul 2021+	* Added quantified constraint to MonadTrans (for GHC >= 8.6)+	* Added Generic and Data instances+	* Added handleE, tryE and finallyE to Control.Monad.Trans.Except+	* Added hoistMaybe to Control.Monad.Trans.Maybe+	* Added Generic and Data instances+	* Added pass-throughs to instances for Backwards+	* Made Lift's <*> lazier+	* Remove long-deprecated selectToCont+	* Remove long-deprecated Control.Monad.Trans.Error+	* Remove long-deprecated Control.Monad.Trans.List++0.5.6.2 Ross Paterson <R.Paterson@city.ac.uk> Feb 2019+	* Further backward compatability fix++0.5.6.1 Ross Paterson <R.Paterson@city.ac.uk> Feb 2019+	* Backward compatability fix for MonadFix ListT instance++0.5.6.0 Ross Paterson <R.Paterson@city.ac.uk> Feb 2019+	* Generalized type of except+	* Added Control.Monad.Trans.Writer.CPS and Control.Monad.Trans.RWS.CPS+	* Added Contravariant instances+	* Added MonadFix instance for ListT++0.5.5.0 Ross Paterson <R.Paterson@city.ac.uk> Oct 2017+	* Added mapSelect and mapSelectT+	* Renamed selectToCont to selectToContT for consistency+	* Defined explicit method definitions to fix space leaks+	* Added missing Semigroup instance to `Constant` functor++0.5.4.0 Ross Paterson <R.Paterson@city.ac.uk> Feb 2017+	* Migrate Bifoldable and Bitraversable instances for Constant++0.5.3.1 Ross Paterson <R.Paterson@city.ac.uk> Feb 2017+	* Fixed for pre-AMP environments++0.5.3.0 Ross Paterson <R.Paterson@city.ac.uk> Feb 2017+	* Added AccumT and SelectT monad transformers+	* Deprecated ListT+	* Added Monad (and related) instances for Reverse+	* Added elimLift and eitherToErrors+	* Added specialized definitions of several methods for efficiency+	* Removed specialized definition of sequenceA for Reverse+	* Backported Eq1/Ord1/Read1/Show1 instances for Proxy++0.5.2.0 Ross Paterson <R.Paterson@city.ac.uk> Feb 2016+	* Re-added orphan instances for Either to deprecated module+	* Added lots of INLINE pragmas++0.5.1.0 Ross Paterson <R.Paterson@city.ac.uk> Jan 2016+	* Bump minor version number, required by added instances++0.5.0.2 Ross Paterson <R.Paterson@city.ac.uk> Jan 2016+	* Backported extra instances for Identity++0.5.0.1 Ross Paterson <R.Paterson@city.ac.uk> Jan 2016+	* Tightened GHC bounds for PolyKinds and DeriveDataTypeable+ 0.5.0.0 Ross Paterson <R.Paterson@city.ac.uk> Dec 2015 	* Control.Monad.IO.Class in base for GHC >= 8.0 	* Data.Functor.{Classes,Compose,Product,Sum} in base for GHC >= 8.0
+ images/bind-AccumT.svg view
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+ images/bind-ReaderT.svg view
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+ images/bind-WriterT.svg view
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legacy/pre709/Data/Functor/Identity.hs view
@@ -1,16 +1,22 @@ {-# LANGUAGE CPP #-}-#if __GLASGOW_HASKELL__ >= 612+#if __GLASGOW_HASKELL__ >= 700 {-# LANGUAGE DeriveDataTypeable #-} #endif #if __GLASGOW_HASKELL__ >= 702 {-# LANGUAGE DeriveGeneric #-} {-# LANGUAGE Trustworthy #-} #endif+#if __GLASGOW_HASKELL__ >= 706+{-# LANGUAGE PolyKinds #-}+#endif #if __GLASGOW_HASKELL__ >= 708 {-# LANGUAGE AutoDeriveTypeable #-} {-# LANGUAGE DataKinds #-}-{-# LANGUAGE PolyKinds #-} #endif+#if MIN_VERSION_base(4,7,0)+-- We need to implement bitSize for the Bits instance, but it's deprecated.+{-# OPTIONS_GHC -fno-warn-deprecations #-}+#endif ----------------------------------------------------------------------------- -- | -- Module      :  Data.Functor.Identity@@ -39,28 +45,33 @@     Identity(..),   ) where +import Data.Bits import Control.Applicative+import Control.Arrow (Arrow((***))) import Control.Monad.Fix #if MIN_VERSION_base(4,4,0) import Control.Monad.Zip (MonadZip(mzipWith, munzip)) #endif import Data.Foldable (Foldable(foldMap)) import Data.Monoid (Monoid(mempty, mappend))+import Data.String (IsString(fromString)) import Data.Traversable (Traversable(traverse))-#if __GLASGOW_HASKELL__ >= 612+#if __GLASGOW_HASKELL__ >= 700 import Data.Data #endif-#if __GLASGOW_HASKELL__ >= 702+import Data.Ix (Ix(..))+import Foreign (Storable(..), castPtr)+#if __GLASGOW_HASKELL__ >= 704 import GHC.Generics #endif  -- | Identity functor and monad. (a non-strict monad) newtype Identity a = Identity { runIdentity :: a }     deriving ( Eq, Ord-#if __GLASGOW_HASKELL__ >= 612+#if __GLASGOW_HASKELL__ >= 700              , Data, Typeable #endif-#if __GLASGOW_HASKELL__ >= 702+#if __GLASGOW_HASKELL__ >= 704              , Generic #endif #if __GLASGOW_HASKELL__ >= 706@@ -68,9 +79,144 @@ #endif              ) +instance (Bits a) => Bits (Identity a) where+    Identity x .&. Identity y     = Identity (x .&. y)+    Identity x .|. Identity y     = Identity (x .|. y)+    xor (Identity x) (Identity y) = Identity (xor x y)+    complement   (Identity x)     = Identity (complement x)+    shift        (Identity x) i   = Identity (shift    x i)+    rotate       (Identity x) i   = Identity (rotate   x i)+    setBit       (Identity x) i   = Identity (setBit   x i)+    clearBit     (Identity x) i   = Identity (clearBit x i)+    shiftL       (Identity x) i   = Identity (shiftL   x i)+    shiftR       (Identity x) i   = Identity (shiftR   x i)+    rotateL      (Identity x) i   = Identity (rotateL  x i)+    rotateR      (Identity x) i   = Identity (rotateR  x i)+    testBit      (Identity x) i   = testBit x i+    bitSize      (Identity x)     = bitSize x+    isSigned     (Identity x)     = isSigned x+    bit i                         = Identity (bit i)+#if MIN_VERSION_base(4,5,0)+    unsafeShiftL (Identity x) i   = Identity (unsafeShiftL x i)+    unsafeShiftR (Identity x) i   = Identity (unsafeShiftR x i)+    popCount     (Identity x)     = popCount x+#endif+#if MIN_VERSION_base(4,7,0)+    zeroBits                      = Identity zeroBits+    bitSizeMaybe (Identity x)     = bitSizeMaybe x+#endif++instance (Bounded a) => Bounded (Identity a) where+    minBound = Identity minBound+    maxBound = Identity maxBound++instance (Enum a) => Enum (Identity a) where+    succ (Identity x)     = Identity (succ x)+    pred (Identity x)     = Identity (pred x)+    toEnum i              = Identity (toEnum i)+    fromEnum (Identity x) = fromEnum x+    enumFrom (Identity x) = map Identity (enumFrom x)+    enumFromThen (Identity x) (Identity y) = map Identity (enumFromThen x y)+    enumFromTo   (Identity x) (Identity y) = map Identity (enumFromTo   x y)+    enumFromThenTo (Identity x) (Identity y) (Identity z) =+        map Identity (enumFromThenTo x y z)++#if MIN_VERSION_base(4,7,0)+instance (FiniteBits a) => FiniteBits (Identity a) where+    finiteBitSize (Identity x) = finiteBitSize x+#endif++instance (Floating a) => Floating (Identity a) where+    pi                                = Identity pi+    exp   (Identity x)                = Identity (exp x)+    log   (Identity x)                = Identity (log x)+    sqrt  (Identity x)                = Identity (sqrt x)+    sin   (Identity x)                = Identity (sin x)+    cos   (Identity x)                = Identity (cos x)+    tan   (Identity x)                = Identity (tan x)+    asin  (Identity x)                = Identity (asin x)+    acos  (Identity x)                = Identity (acos x)+    atan  (Identity x)                = Identity (atan x)+    sinh  (Identity x)                = Identity (sinh x)+    cosh  (Identity x)                = Identity (cosh x)+    tanh  (Identity x)                = Identity (tanh x)+    asinh (Identity x)                = Identity (asinh x)+    acosh (Identity x)                = Identity (acosh x)+    atanh (Identity x)                = Identity (atanh x)+    Identity x ** Identity y          = Identity (x ** y)+    logBase (Identity x) (Identity y) = Identity (logBase x y)++instance (Fractional a) => Fractional (Identity a) where+    Identity x / Identity y = Identity (x / y)+    recip (Identity x)      = Identity (recip x)+    fromRational r          = Identity (fromRational r)++instance (IsString a) => IsString (Identity a) where+    fromString s = Identity (fromString s)++instance (Ix a) => Ix (Identity a) where+    range     (Identity x, Identity y) = map Identity (range (x, y))+    index     (Identity x, Identity y) (Identity i) = index     (x, y) i+    inRange   (Identity x, Identity y) (Identity e) = inRange   (x, y) e+    rangeSize (Identity x, Identity y) = rangeSize (x, y)++instance (Integral a) => Integral (Identity a) where+    quot    (Identity x) (Identity y) = Identity (quot x y)+    rem     (Identity x) (Identity y) = Identity (rem  x y)+    div     (Identity x) (Identity y) = Identity (div  x y)+    mod     (Identity x) (Identity y) = Identity (mod  x y)+    quotRem (Identity x) (Identity y) = (Identity *** Identity) (quotRem x y)+    divMod  (Identity x) (Identity y) = (Identity *** Identity) (divMod  x y)+    toInteger (Identity x)            = toInteger x+ instance (Monoid a) => Monoid (Identity a) where     mempty = Identity mempty     mappend (Identity x) (Identity y) = Identity (mappend x y)++instance (Num a) => Num (Identity a) where+    Identity x + Identity y = Identity (x + y)+    Identity x - Identity y = Identity (x - y)+    Identity x * Identity y = Identity (x * y)+    negate (Identity x)     = Identity (negate x)+    abs    (Identity x)     = Identity (abs    x)+    signum (Identity x)     = Identity (signum x)+    fromInteger n           = Identity (fromInteger n)++instance (Real a) => Real (Identity a) where+    toRational (Identity x) = toRational x++instance (RealFloat a) => RealFloat (Identity a) where+    floatRadix     (Identity x)     = floatRadix     x+    floatDigits    (Identity x)     = floatDigits    x+    floatRange     (Identity x)     = floatRange     x+    decodeFloat    (Identity x)     = decodeFloat    x+    exponent       (Identity x)     = exponent       x+    isNaN          (Identity x)     = isNaN          x+    isInfinite     (Identity x)     = isInfinite     x+    isDenormalized (Identity x)     = isDenormalized x+    isNegativeZero (Identity x)     = isNegativeZero x+    isIEEE         (Identity x)     = isIEEE         x+    significand    (Identity x)     = significand (Identity x)+    scaleFloat s   (Identity x)     = Identity (scaleFloat s x)+    encodeFloat m n                 = Identity (encodeFloat m n)+    atan2 (Identity x) (Identity y) = Identity (atan2 x y)++instance (RealFrac a) => RealFrac (Identity a) where+    properFraction (Identity x) = (id *** Identity) (properFraction x)+    truncate       (Identity x) = truncate x+    round          (Identity x) = round    x+    ceiling        (Identity x) = ceiling  x+    floor          (Identity x) = floor    x++instance (Storable a) => Storable (Identity a) where+    sizeOf    (Identity x)       = sizeOf x+    alignment (Identity x)       = alignment x+    peekElemOff p i              = fmap Identity (peekElemOff (castPtr p) i)+    pokeElemOff p i (Identity x) = pokeElemOff (castPtr p) i x+    peekByteOff p i              = fmap Identity (peekByteOff p i)+    pokeByteOff p i (Identity x) = pokeByteOff p i x+    peek p                       = fmap runIdentity (peek (castPtr p))+    poke p (Identity x)          = poke (castPtr p) x  -- These instances would be equivalent to the derived instances of the -- newtype if the field were removed.
legacy/pre711/Data/Functor/Classes.hs view
@@ -69,6 +69,9 @@ import Control.Applicative (Const(Const)) import Data.Functor.Identity (Identity(Identity)) import Data.Monoid (mappend)+#if MIN_VERSION_base(4,7,0)+import Data.Proxy (Proxy(Proxy))+#endif #if __GLASGOW_HASKELL__ >= 708 import Data.Typeable #endif@@ -357,6 +360,21 @@  instance (Show a) => Show1 (Either a) where     liftShowsPrec = liftShowsPrec2 showsPrec showList++#if MIN_VERSION_base(4,7,0)+instance Eq1 Proxy where+    liftEq _ _ _ = True++instance Ord1 Proxy where+    liftCompare _ _ _ = EQ++instance Show1 Proxy where+    liftShowsPrec _ _ _ _ = showString "Proxy"++instance Read1 Proxy where+    liftReadsPrec _ _ d =+        readParen (d > 10) (\r -> [(Proxy, s) | ("Proxy",s) <- lex r ])+#endif  -- Instances for other functors defined in the base package
legacy/pre711/Data/Functor/Compose.hs view
@@ -7,7 +7,7 @@ {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeOperators #-} #endif-#if __GLASGOW_HASKELL__ >= 704+#if __GLASGOW_HASKELL__ >= 706 {-# LANGUAGE PolyKinds #-} #endif #if __GLASGOW_HASKELL__ >= 708@@ -35,6 +35,9 @@   ) where  import Data.Functor.Classes+#if MIN_VERSION_base(4,12,0)+import Data.Functor.Contravariant+#endif  import Control.Applicative #if __GLASGOW_HASKELL__ >= 708@@ -42,7 +45,7 @@ #endif import Data.Foldable (Foldable(foldMap)) import Data.Traversable (Traversable(traverse))-#if __GLASGOW_HASKELL__ >= 702+#if __GLASGOW_HASKELL__ >= 704 import GHC.Generics #endif @@ -53,7 +56,7 @@ -- but the composition of monads is not always a monad. newtype Compose f g a = Compose { getCompose :: f (g a) } -#if __GLASGOW_HASKELL__ >= 702+#if __GLASGOW_HASKELL__ >= 704 deriving instance Generic (Compose f g a)  instance Functor f => Generic1 (Compose f g) where@@ -144,3 +147,8 @@ instance (Alternative f, Applicative g) => Alternative (Compose f g) where     empty = Compose empty     Compose x <|> Compose y = Compose (x <|> y)++#if MIN_VERSION_base(4,12,0)+instance (Functor f, Contravariant g) => Contravariant (Compose f g) where+    contramap f (Compose fga) = Compose (fmap (contramap f) fga)+#endif
legacy/pre711/Data/Functor/Product.hs view
@@ -7,7 +7,7 @@ {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeOperators #-} #endif-#if __GLASGOW_HASKELL__ >= 704+#if __GLASGOW_HASKELL__ >= 706 {-# LANGUAGE PolyKinds #-} #endif #if __GLASGOW_HASKELL__ >= 708@@ -45,16 +45,19 @@ #endif import Data.Foldable (Foldable(foldMap)) import Data.Functor.Classes+#if MIN_VERSION_base(4,12,0)+import Data.Functor.Contravariant+#endif import Data.Monoid (mappend) import Data.Traversable (Traversable(traverse))-#if __GLASGOW_HASKELL__ >= 702+#if __GLASGOW_HASKELL__ >= 704 import GHC.Generics #endif  -- | Lifted product of functors. data Product f g a = Pair (f a) (g a) -#if __GLASGOW_HASKELL__ >= 702+#if __GLASGOW_HASKELL__ >= 704 deriving instance Generic (Product f g a)  instance Generic1 (Product f g) where@@ -145,4 +148,9 @@ #if MIN_VERSION_base(4,4,0) instance (MonadZip f, MonadZip g) => MonadZip (Product f g) where     mzipWith f (Pair x1 y1) (Pair x2 y2) = Pair (mzipWith f x1 x2) (mzipWith f y1 y2)+#endif++#if MIN_VERSION_base(4,12,0)+instance (Contravariant f, Contravariant g) => Contravariant (Product f g) where+    contramap f (Pair a b) = Pair (contramap f a) (contramap f b) #endif
legacy/pre711/Data/Functor/Sum.hs view
@@ -7,7 +7,7 @@ {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeOperators #-} #endif-#if __GLASGOW_HASKELL__ >= 704+#if __GLASGOW_HASKELL__ >= 706 {-# LANGUAGE PolyKinds #-} #endif #if __GLASGOW_HASKELL__ >= 708@@ -40,16 +40,19 @@ #endif import Data.Foldable (Foldable(foldMap)) import Data.Functor.Classes+#if MIN_VERSION_base(4,12,0)+import Data.Functor.Contravariant+#endif import Data.Monoid (mappend) import Data.Traversable (Traversable(traverse))-#if __GLASGOW_HASKELL__ >= 702+#if __GLASGOW_HASKELL__ >= 704 import GHC.Generics #endif  -- | Lifted sum of functors. data Sum f g a = InL (f a) | InR (g a) -#if __GLASGOW_HASKELL__ >= 702+#if __GLASGOW_HASKELL__ >= 704 deriving instance Generic (Sum f g a)  instance Generic1 (Sum f g) where@@ -125,3 +128,9 @@ instance (Traversable f, Traversable g) => Traversable (Sum f g) where     traverse f (InL x) = InL <$> traverse f x     traverse f (InR y) = InR <$> traverse f y++#if MIN_VERSION_base(4,12,0)+instance (Contravariant f, Contravariant g) => Contravariant (Sum f g) where+    contramap f (InL xs) = InL (contramap f xs)+    contramap f (InR ys) = InR (contramap f ys)+#endif
transformers.cabal view
@@ -1,5 +1,5 @@ name:         transformers-version:      0.5.0.0+version:      0.6.3.0 license:      BSD3 license-file: LICENSE author:       Andy Gill, Ross Paterson@@ -9,7 +9,9 @@ synopsis:     Concrete functor and monad transformers description:     A portable library of functor and monad transformers, inspired by-    the paper \"Functional Programming with Overloading and Higher-Order+    the paper+    .+    * \"Functional Programming with Overloading and Higher-Order     Polymorphism\", by Mark P Jones,     in /Advanced School of Functional Programming/, 1995     (<http://web.cecs.pdx.edu/~mpj/pubs/springschool.html>).@@ -17,7 +19,6 @@     This package contains:     .     * the monad transformer class (in "Control.Monad.Trans.Class")-      and IO monad class (in "Control.Monad.IO.Class")     .     * concrete functor and monad transformers, each with associated       operations and functions to lift operations associated with other@@ -30,24 +31,28 @@     the @mtl@ or @monads-tf@ packages, which automatically lift operations     introduced by monad transformers through other transformers. build-type: Simple-extra-source-files:+extra-doc-files:     changelog-cabal-version: >= 1.6+    images/bind-AccumT.svg+    images/bind-ReaderT.svg+    images/bind-WriterT.svg+cabal-version: 1.18  source-repository head   type: darcs   location: http://hub.darcs.net/ross/transformers  library+  default-language: Haskell2010   build-depends: base >= 2 && < 6   hs-source-dirs: .-  if !impl(ghc>=7.9)+  if impl(ghc<7.9)     -- Data.Functor.Identity was moved into base-4.8.0.0 (GHC 7.10)     -- see also https://ghc.haskell.org/trac/ghc/ticket/9664     -- NB: using impl(ghc>=7.9) instead of fragile Cabal flags     hs-source-dirs: legacy/pre709     exposed-modules: Data.Functor.Identity-  if !impl(ghc>=7.11)+  if impl(ghc<7.11)     -- modules moved into base-4.9.0 (GHC 8.0)     -- see https://ghc.haskell.org/trac/ghc/ticket/10773     -- see https://ghc.haskell.org/trac/ghc/ticket/11135@@ -60,26 +65,28 @@       Data.Functor.Sum   if impl(ghc>=7.2 && <7.5)     -- Prior to GHC 7.5, GHC.Generics lived in ghc-prim-    build-depends: ghc-prim+    build-depends: ghc-prim < 0.3   exposed-modules:     Control.Applicative.Backwards     Control.Applicative.Lift     Control.Monad.Signatures+    Control.Monad.Trans.Accum     Control.Monad.Trans.Class     Control.Monad.Trans.Cont     Control.Monad.Trans.Except-    Control.Monad.Trans.Error     Control.Monad.Trans.Identity-    Control.Monad.Trans.List     Control.Monad.Trans.Maybe     Control.Monad.Trans.Reader     Control.Monad.Trans.RWS+    Control.Monad.Trans.RWS.CPS     Control.Monad.Trans.RWS.Lazy     Control.Monad.Trans.RWS.Strict+    Control.Monad.Trans.Select     Control.Monad.Trans.State     Control.Monad.Trans.State.Lazy     Control.Monad.Trans.State.Strict     Control.Monad.Trans.Writer+    Control.Monad.Trans.Writer.CPS     Control.Monad.Trans.Writer.Lazy     Control.Monad.Trans.Writer.Strict     Data.Functor.Constant