transformers 0.6.1.2 → 0.6.3.0

raw patch · 9 files changed

Files

• Control/Monad/Trans/Accum.hs +14/−14
• Control/Monad/Trans/Cont.hs +3/−1
• Control/Monad/Trans/Except.hs +13/−10
• Control/Monad/Trans/Maybe.hs +2/−2
• Control/Monad/Trans/Reader.hs +3/−1
• Control/Monad/Trans/Select.hs +8/−10
• Control/Monad/Trans/State/Lazy.hs +14/−0
• changelog +8/−0
• transformers.cabal +3/−4

@@ -35,8 +35,7 @@     evalAccum,     mapAccum,     -- * The AccumT monad transformer-    AccumT(AccumT),-    runAccumT,+    AccumT(..),     execAccumT,     evalAccumT,     mapAccumT,@@ -78,7 +77,8 @@ #endif  -- ------------------------------------------------------------------------------ | An accumulation monad parameterized by the type @w@ of output to accumulate.+-- | 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@@ -145,20 +145,20 @@ -- 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.-newtype AccumT w m a = AccumT (w -> m (a, w))+--+-- @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---- | 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 :: AccumT w m a -> w -> m (a, w)-runAccumT (AccumT f) = f-{-# INLINE runAccumT #-}  -- | Extract the output from an accumulation computation. --

@@ -64,7 +64,7 @@ #endif  {- |-Continuation monad.+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@.@@ -139,6 +139,8 @@ -- -- '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)

@@ -36,8 +36,7 @@     mapExcept,     withExcept,     -- * The ExceptT monad transformer-    ExceptT(ExceptT),-    runExceptT,+    ExceptT(..),     mapExceptT,     withExceptT,     -- * Exception operations@@ -46,6 +45,7 @@     handleE,     tryE,     finallyE,+    onE,     -- * Lifting other operations     liftCallCC,     liftListen,@@ -79,7 +79,7 @@ import GHC.Generics #endif --- | The parameterizable exception monad.+-- | The parameterizable exception monad, which is strict. -- -- Computations are either exceptions (of any type) or normal values. -- These computations are plain values, and are unrelated to the@@ -119,7 +119,7 @@  -- | 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 - An arbitrary exception type. --@@ -131,7 +131,7 @@ -- 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@@ -170,11 +170,6 @@ 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-{-# INLINE runExceptT #-}- -- | Map the unwrapped computation using the given function. -- -- * @'runExceptT' ('mapExceptT' f m) = f ('runExceptT' m)@@@ -334,6 +329,14 @@     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

@@ -69,8 +69,8 @@ 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. --

@@ -71,7 +71,7 @@ import GHC.Generics #endif --- | The parameterizable reader monad.+-- | The parameterizable reader monad, which is non-strict. -- -- Computations are functions of a shared environment. --@@ -122,6 +122,8 @@ -- -- <<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)

@@ -37,8 +37,7 @@     runSelect,     mapSelect,     -- * The SelectT monad transformer-    SelectT(SelectT),-    runSelectT,+    SelectT(..),     mapSelectT,     -- * Monad transformation     selectToContT,@@ -58,7 +57,7 @@ import GHC.Generics #endif --- | Selection monad.+-- | The selection monad, which is non-strict. type Select r = SelectT r Identity  -- | Constructor for computations in the selection monad.@@ -83,16 +82,15 @@ -- -- 'SelectT' is not a functor on the category of monads, and many operations -- cannot be lifted through it.-newtype SelectT r m a = SelectT ((a -> m r) -> m a)+--+-- @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---- | Runs a @SelectT@ computation with a function for evaluating answers--- to select a particular answer.  (The inverse of 'select'.)-runSelectT :: SelectT r m a -> (a -> m r) -> m a-runSelectT (SelectT g) = g-{-# INLINE runSelectT #-}  -- | Apply a function to transform the result of a selection computation. -- This has a more restricted type than the @map@ operations for other

@@ -64,6 +64,9 @@     liftCatch,     liftListen,     liftPass,+    -- * Conversion to and from the strict version+    strictToLazyStateT,+    lazyToStrictStateT,     -- * Examples     -- ** State monads     -- $examples@@ -78,6 +81,7 @@ 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@@ -357,6 +361,16 @@     ~((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 

@@ -1,5 +1,13 @@ -*-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

@@ -1,5 +1,5 @@ name:         transformers-version:      0.6.1.2+version:      0.6.3.0 license:      BSD3 license-file: LICENSE author:       Andy Gill, Ross Paterson@@ -32,11 +32,10 @@     introduced by monad transformers through other transformers. build-type: Simple extra-doc-files:+    changelog     images/bind-AccumT.svg     images/bind-ReaderT.svg     images/bind-WriterT.svg-extra-source-files:-    changelog cabal-version: 1.18  source-repository head@@ -66,7 +65,7 @@       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