free 4.7 → 4.7.1

raw patch · 6 files changed

+72/−9 lines, 6 filesPVP ok

version bump matches the API change (PVP)

API changes (from Hackage documentation)

Files

• CHANGELOG.markdown +4/−0
• free.cabal +1/−1
• src/Control/Monad/Free.hs +19/−0
• src/Control/Monad/Trans/Free.hs +20/−0
• src/Control/Monad/Trans/Free/Church.hs +18/−0
• src/Control/Monad/Trans/Iter.hs +10/−8

@@ -1,3 +1,7 @@+4.7.1+-----+* Added more versions of `cutoff`.+ 4.7 --- * Added `prelude-extras` support. This makes it possible to work without `UndecidableInstances` for most operations.

@@ -1,6 +1,6 @@ name:          free category:      Control, Monads-version:       4.7+version:       4.7.1 license:       BSD3 cabal-version: >= 1.10 license-file:  LICENSE

@@ -28,6 +28,7 @@   , iterM   , hoistFree   , toFreeT+  , cutoff   , _Pure, _Free   ) where @@ -293,6 +294,24 @@ toFreeT :: (Functor f, Monad m) => Free f a -> FreeT.FreeT f m a toFreeT (Pure a) = FreeT.FreeT (return (FreeT.Pure a)) toFreeT (Free f) = FreeT.FreeT (return (FreeT.Free (fmap toFreeT f)))++-- | Cuts off a tree of computations at a given depth.+-- If the depth is 0 or less, no computation nor+-- monadic effects will take place.+--+-- Some examples (n ≥ 0):+--+-- prop> cutoff 0     _        == return Nothing+-- prop> cutoff (n+1) . return == return . Just+-- prop> cutoff (n+1) . lift   ==   lift . liftM Just+-- prop> cutoff (n+1) . wrap   ==  wrap . fmap (cutoff n)+--+-- Calling 'retract . cutoff n' is always terminating, provided each of the+-- steps in the iteration is terminating.+cutoff :: (Functor f) => Integer -> Free f a -> Free f (Maybe a)+cutoff 0 _ = return Nothing+cutoff n (Free f) = Free $ fmap (cutoff (n - 1)) f+cutoff _ m = Just <$> m  -- | This is @Prism' (Free f a) a@ in disguise --

@@ -39,6 +39,7 @@   , iterTM   , hoistFreeT   , transFreeT+  , cutoff   -- * Operations of free monad   , retract   , iter@@ -331,6 +332,25 @@ -- | Like 'iter' for monadic values. iterM :: (Functor f, Monad m) => (f (m a) -> m a) -> Free f a -> m a iterM phi = iterT phi . hoistFreeT (return . runIdentity)++-- | Cuts off a tree of computations at a given depth.+-- If the depth is @0@ or less, no computation nor+-- monadic effects will take place.+--+-- Some examples (@n ≥ 0@):+--+-- @+-- 'cutoff' 0     _        ≡ 'return' 'Nothing'+-- 'cutoff' (n+1) '.' 'return' ≡ 'return' '.' 'Just'+-- 'cutoff' (n+1) '.' 'lift'   ≡ 'lift' '.' 'liftM' 'Just'+-- 'cutoff' (n+1) '.' 'wrap'   ≡ 'wrap' '.' 'fmap' ('cutoff' n)+-- @+--+-- Calling @'retract' '.' 'cutoff' n@ is always terminating, provided each of the+-- steps in the iteration is terminating.+cutoff :: (Functor f, Monad m) => Integer -> FreeT f m a -> FreeT f m (Maybe a)+cutoff 0 _ = return Nothing+cutoff n (FreeT m) = FreeT $ bimap Just (cutoff (n - 1)) `liftM` m  #if __GLASGOW_HASKELL__ < 707 instance Typeable1 f => Typeable2 (FreeF f) where

@@ -33,6 +33,7 @@   , iterTM   , hoistFT   , transFT+  , cutoff   -- * Operations of free monad   , improve   , fromF, toF@@ -55,6 +56,7 @@ import Control.Monad.Cont.Class import Control.Monad.Free.Class import Control.Monad.Trans.Free (FreeT(..), FreeF(..), Free)+import qualified Control.Monad.Trans.Free as FreeT import Data.Foldable (Foldable) import qualified Data.Foldable as F import Data.Traversable (Traversable)@@ -192,6 +194,22 @@ -- | Lift a natural transformation from @f@ to @g@ into a monad homomorphism from @'FT' f m@ to @'FT' g n@ transFT :: (Monad m, Functor g) => (forall a. f a -> g a) -> FT f m b -> FT g m b transFT phi (FT m) = FT (\kp kf -> m kp (kf . phi))++-- | Cuts off a tree of computations at a given depth.+-- If the depth is 0 or less, no computation nor+-- monadic effects will take place.+--+-- Some examples (n ≥ 0):+--+-- prop> cutoff 0     _        == return Nothing+-- prop> cutoff (n+1) . return == return . Just+-- prop> cutoff (n+1) . lift   ==   lift . liftM Just+-- prop> cutoff (n+1) . wrap   ==  wrap . fmap (cutoff n)+--+-- Calling 'retract . cutoff n' is always terminating, provided each of the+-- steps in the iteration is terminating.+cutoff :: (Functor f, Monad m) => Integer -> FT f m a -> FT f m (Maybe a)+cutoff n = toFT . FreeT.cutoff n . fromFT  -- | -- 'retract' is the left inverse of 'liftF'

@@ -303,15 +303,17 @@ -- -- The step where the final value is produced also counts towards the limit. ----- Some examples (n ≥ 0):+-- Some examples (@n ≥ 0@): ----- prop> cutoff 0     _        == return Nothing--- prop> cutoff (n+1) . return == return . Just--- prop> cutoff (n+1) . lift   ==   lift . liftM Just--- prop> cutoff (n+1) . delay  ==  delay . cutoff n--- prop> cutoff n     never    == iterate delay (return Nothing) !! n+-- @+-- 'cutoff' 0     _        ≡ 'return' 'Nothing'+-- 'cutoff' (n+1) '.' 'return' ≡ 'return' '.' 'Just'+-- 'cutoff' (n+1) '.' 'lift'   ≡ 'lift' '.' 'liftM' 'Just'+-- 'cutoff' (n+1) '.' 'delay'  ≡ 'delay' . 'cutoff' n+-- 'cutoff' n     'never'    ≡ 'iterate' 'delay' ('return' 'Nothing') '!!' n+-- @ ----- Calling 'retract . cutoff n' is always terminating, provided each of the+-- Calling @'retract' '.' 'cutoff' n@ is always terminating, provided each of the -- steps in the iteration is terminating. cutoff :: (Monad m) => Integer -> IterT m a -> IterT m (Maybe a) cutoff n | n <= 0 = const $ return Nothing@@ -337,7 +339,7 @@ --   The resulting computation has as many steps as the longest computation --   in the list. -----   Equivalent to @void . interleave@.+--   Equivalent to @'void' '.' 'interleave'@. interleave_ :: (Monad m) => [IterT m a] -> IterT m () interleave_ [] = return () interleave_ xs = IterT $ liftM (Right . interleave_ . rights) $ mapM runIterT xs