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Diffstat (limited to 'third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/Writer/Strict.hs')
| -rw-r--r-- | third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/Writer/Strict.hs | 316 |
1 files changed, 0 insertions, 316 deletions
diff --git a/third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/Writer/Strict.hs b/third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/Writer/Strict.hs deleted file mode 100644 index f39862c020..0000000000 --- a/third_party/bazel/rules_haskell/examples/transformers/Control/Monad/Trans/Writer/Strict.hs +++ /dev/null @@ -1,316 +0,0 @@ -{-# LANGUAGE CPP #-} -#if __GLASGOW_HASKELL__ >= 702 -{-# LANGUAGE Safe #-} -#endif -#if __GLASGOW_HASKELL__ >= 710 -{-# LANGUAGE AutoDeriveTypeable #-} -#endif ------------------------------------------------------------------------------ --- | --- Module : Control.Monad.Trans.Writer.Strict --- 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 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; for a lazy version with --- 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.Writer.CPS" instead. ------------------------------------------------------------------------------ - -module Control.Monad.Trans.Writer.Strict ( - -- * The Writer monad - Writer, - writer, - runWriter, - execWriter, - mapWriter, - -- * The WriterT monad transformer - WriterT(..), - execWriterT, - mapWriterT, - -- * Writer operations - tell, - listen, - listens, - pass, - censor, - -- * Lifting other operations - liftCallCC, - liftCatch, - ) where - -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 -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(4,4,0) -import Control.Monad.Zip (MonadZip(mzipWith)) -#endif -import Data.Foldable -import Data.Monoid -import Data.Traversable (Traversable(traverse)) -import Prelude hiding (null, length) - --- --------------------------------------------------------------------------- --- | 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'. -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. --- --- * @'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: --- --- * @w@ - the output to accumulate. --- --- * @m@ - The inner monad. --- --- The 'return' function produces the output 'mempty', while @>>=@ --- combines the outputs of the subcomputations using 'mappend'. -newtype WriterT w m a = WriterT { runWriterT :: m (a, w) } - -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 $ - readsUnaryWith (liftReadsPrec rp' rl') "WriterT" WriterT - where - rp' = liftReadsPrec2 rp rl readsPrec readList - rl' = liftReadList2 rp rl readsPrec readList - -instance (Show w, Show1 m) => Show1 (WriterT w m) where - liftShowsPrec sp sl d (WriterT m) = - showsUnaryWith (liftShowsPrec sp' sl') "WriterT" d m - where - sp' = liftShowsPrec2 sp sl showsPrec showList - sl' = liftShowList2 sp sl showsPrec showList - -instance (Eq w, Eq1 m, Eq a) => Eq (WriterT w m a) where (==) = eq1 -instance (Ord w, Ord1 m, Ord a) => Ord (WriterT w m a) where compare = compare1 -instance (Read w, Read1 m, Read a) => Read (WriterT w m a) where - readsPrec = readsPrec1 -instance (Show w, Show1 m, Show a) => Show (WriterT w m a) where - showsPrec = showsPrec1 - --- | Extract the output from a writer computation. --- --- * @'execWriterT' m = 'liftM' 'snd' ('runWriterT' m)@ -execWriterT :: (Monad m) => 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 :: (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. --- --- * @'runWriterT' ('listen' m) = 'liftM' (\\ (a, w) -> ((a, w), w)) ('runWriterT' m)@ -listen :: (Monad m) => WriterT w m a -> WriterT w m (a, w) -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. --- --- * @'listens' f m = 'liftM' (id *** f) ('listen' m)@ --- --- * @'runWriterT' ('listens' f m) = 'liftM' (\\ (a, w) -> ((a, f w), w)) ('runWriterT' m)@ -listens :: (Monad m) => (w -> b) -> WriterT w m a -> WriterT w m (a, b) -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 --- to the output. --- --- * @'runWriterT' ('pass' m) = 'liftM' (\\ ((a, f), w) -> (a, f w)) ('runWriterT' m)@ -pass :: (Monad m) => WriterT w m (a, w -> w) -> WriterT w m a -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 --- unchanged. --- --- * @'censor' f m = 'pass' ('liftM' (\\ x -> (x,f)) m)@ --- --- * @'runWriterT' ('censor' f m) = 'liftM' (\\ (a, w) -> (a, f w)) ('runWriterT' m)@ -censor :: (Monad m) => (w -> w) -> WriterT w m a -> WriterT w m a -censor f m = WriterT $ do - (a, w) <- runWriterT m - return (a, f w) -{-# INLINE censor #-} - --- | Lift a @callCC@ operation to the new monad. -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. -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 #-} |