0f9f8fc · typeable/ether

git.iko.soy/typeable/ether

MonadExcept instance for WrappedEther

commit0f9f8fc0d93deb09df5849c900d9420ff8248600 authorIndex Int <vlad.z.4096@gmail.com> dateFri 12 Jun 2015, 02:00 (11 years ago) parent5289d99

2 files changed+9

unifiedsplit

src/Control/Ether/Wrapped.hs+6

@@ -13,9 +13,11 @@ import Control.Monad.Fix (MonadFix)

1313import Control.Monad.IO.Class (MonadIO)

1414import Control.Monad.Ether.Reader

1515import Control.Monad.Ether.State

16+import Control.Monad.Ether.Except

1617

1718import qualified Control.Monad.Reader as Class

1819import qualified Control.Monad.State as Class

20+import qualified Control.Monad.Except as Class

1921

2022newtype WrappedEther tag m a = WrapEther { unwrapEther :: m a }

2123 deriving ( Functor, Applicative, Alternative, Monad, MonadPlus

@@ -29,5 +31,9 @@ instance MonadState tag s m => Class.MonadState s (WrappedEther tag m) where

2931 get = WrapEther $ get (Proxy :: Proxy tag)

3032 put = WrapEther . put (Proxy :: Proxy tag)

3133

34+instance MonadExcept tag e m => Class.MonadError e (WrappedEther tag m) where

35+ throwError = WrapEther . throw (Proxy :: Proxy tag)

36+ catchError m h = WrapEther $ catch (Proxy :: Proxy tag) (unwrapEther m) (unwrapEther . h)

37+

3238ethered :: proxy tag -> WrappedEther tag m a -> m a

3339ethered _proxy = unwrapEther

src/Control/Monad/Ether/Except.hs+3

@@ -44,8 +44,11 @@ import qualified Control.Monad.Trans.Writer.Strict as Trans.W.Strict

4444

4545class Monad m => MonadExcept tag e m | m tag -> e where

4646

47+ -- | Is used within a monadic computation to begin exception processing.

4748 throw :: proxy tag -> e -> m a

4849

50+ -- | A handler function to handle previous exceptions and return to

51+ -- normal execution.

4952 catch :: proxy tag -> m a -> (e -> m a) -> m a

5053

5154instance {-# OVERLAPPING #-} Monad m => MonadExcept tag e (ExceptT tag e m) where