failure 0.1.1 → 0.1.2

raw patch · 3 files changed

+132/−128 lines, 3 filesdep ~basesetup-changedPVP: major bump suggested

API removals or changes: PVP suggests a major version bump

Dependency ranges changed: base

API changes (from Hackage documentation)

Files

• Control/Failure.hs +95/−96
• Setup.lhs +7/−7
• failure.cabal +30/−25

@@ -1,96 +1,95 @@-{-# LANGUAGE Rank2Types #-}-{-# LANGUAGE TypeFamilies #-}-{-# LANGUAGE MultiParamTypeClasses #-}-{-# LANGUAGE FlexibleInstances #-}-{-# LANGUAGE UndecidableInstances #-}-{-# LANGUAGE DeriveDataTypeable #-}-{-# LANGUAGE FlexibleContexts #-}--- | Type classes for returning failures.-module Control.Failure-    ( -- * Type class-      Failure (..)-      -- * Wrapping failures-    , WrapFailure (..)-      -- * Convenience 'String' failure-    , StringException (..)-    , failureString-      -- * Convert 'Failure's into concrete types-    , Try (..)-    , NothingException (..)-    , NullException (..)-    ) where--import Prelude hiding (catch)-import Control.Exception (throwIO, catch, Exception, SomeException (..))-import Data.Typeable (Typeable)-import Control.Monad.Trans.Error ()-import Control.Monad.Trans.Class (MonadTrans (lift))--class Monad f => Failure e f where-    failure :: e -> f v--class Failure e f => WrapFailure e f where-    -- | Wrap the failure value, if any, with the given function. This is-    -- useful in particular when you want all the exceptions returned from a-    -- certain library to be of a certain type, even if they were generated by-    -- a different library.-    wrapFailure :: (forall eIn. Exception eIn => eIn -> e) -> f a -> f a-instance Exception e => WrapFailure e IO where-    wrapFailure f m =-        m `catch` \e@SomeException{} -> throwIO (f e)--class Try f where-  type Error f-  -- Turn a concrete failure into an abstract failure-  try :: Failure (Error f) f' => f a -> f' a---- | Call 'failure' with a 'String'.-failureString :: Failure StringException m => String -> m a-failureString = failure . StringException--newtype StringException = StringException String-    deriving Typeable-instance Show StringException where-    show (StringException s) = "StringException: " ++ s-instance Exception StringException---- ----------------- base instances--- ----------------instance Failure e Maybe where failure _ = Nothing-instance Failure e []    where failure _ = []-instance Failure e (Either e) where failure = Left--instance Exception e => Failure e IO where-  failure = throwIO---- | Instance for all monad transformers, simply lift the @failure@ into the--- base monad.-instance (MonadTrans t, Failure e m, Monad (t m)) => Failure e (t m) where-    failure = lift . failure---- not a monad or applicative instance Failure e (Either e) where failure = Left--data NothingException = NothingException-  deriving (Show, Typeable)-instance Exception NothingException--instance Try Maybe where-  type Error Maybe = NothingException-  try Nothing      = failure NothingException-  try (Just x)     = return x--instance Try (Either e) where-  type Error (Either e) = e-  try (Left  e)         = failure e-  try (Right x)         = return x--data NullException = NullException-  deriving (Show, Typeable)-instance Exception NullException--instance Try [] where-  type Error [] = NullException-  try []        = failure NullException-  try (x:_)     = return x+{-# LANGUAGE Rank2Types #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE UndecidableInstances #-}
+{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE CPP #-}
+-- | Type classes for returning failures.
+module Control.Failure
+    ( -- * Type class
+      Failure (..)
+      -- * Wrapping failures
+    , WrapFailure (..)
+      -- * Convenience 'String' failure
+    , StringException (..)
+    , failureString
+      -- * Convert 'Failure's into concrete types
+    , Try (..)
+    , NothingException (..)
+    , NullException (..)
+    ) where
+
+import Prelude hiding (catch)
+import Control.Exception (throw, catch, Exception, SomeException (..))
+import Data.Typeable (Typeable)
+#if !(MIN_VERSION_base(4,3,0))
+import Control.Monad.Trans.Error ()
+#else
+import Control.Monad.Instances ()
+#endif
+
+class Monad f => Failure e f where
+    failure :: e -> f v
+
+class Failure e f => WrapFailure e f where
+    -- | Wrap the failure value, if any, with the given function. This is
+    -- useful in particular when you want all the exceptions returned from a
+    -- certain library to be of a certain type, even if they were generated by
+    -- a different library.
+    wrapFailure :: (forall eIn. Exception eIn => eIn -> e) -> f a -> f a
+instance Exception e => WrapFailure e IO where
+    wrapFailure f m =
+        m `catch` \e@SomeException{} -> throw (f e)
+
+class Try f where
+  type Error f
+  -- Turn a concrete failure into an abstract failure
+  try :: Failure (Error f) f' => f a -> f' a
+
+-- | Call 'failure' with a 'String'.
+failureString :: Failure StringException m => String -> m a
+failureString = failure . StringException
+
+newtype StringException = StringException String
+    deriving Typeable
+instance Show StringException where
+    show (StringException s) = "StringException: " ++ s
+instance Exception StringException
+
+-- --------------
+-- base instances
+-- --------------
+
+instance Failure e Maybe where failure _ = Nothing
+instance Failure e []    where failure _ = []
+instance Failure e (Either e) where failure = Left
+
+instance Exception e => Failure e IO where
+  failure = Control.Exception.throw
+
+-- not a monad or applicative instance Failure e (Either e) where failure = Left
+
+data NothingException = NothingException
+  deriving (Show, Typeable)
+instance Exception NothingException
+
+instance Try Maybe where
+  type Error Maybe = NothingException
+  try Nothing      = failure NothingException
+  try (Just x)     = return x
+
+instance Try (Either e) where
+  type Error (Either e) = e
+  try (Left  e)         = failure e
+  try (Right x)         = return x
+
+data NullException = NullException
+  deriving (Show, Typeable)
+instance Exception NullException
+
+instance Try [] where
+  type Error [] = NullException
+  try []        = failure NullException
+  try (x:_)     = return x

@@ -1,7 +1,7 @@-#!/usr/bin/env runhaskell--> module Main where-> import Distribution.Simple--> main :: IO ()-> main = defaultMain+#!/usr/bin/env runhaskell
+
+> module Main where
+> import Distribution.Simple
+
+> main :: IO ()
+> main = defaultMain

@@ -1,25 +1,30 @@-name: failure-version: 0.1.1-Cabal-Version:  >= 1.6-build-type: Simple-license: BSD3-author: Pepe Iborra, Michael Snoyman, Nicolas Pouillard-maintainer: pepeiborra@gmail.com-homepage: http://www.haskell.org/haskellwiki/Failure-description: A simple type class for success/failure computations.-synopsis: A simple type class for success/failure computations.-category: Control, Monads, Failure-stability: stable--Library-  buildable: True-  build-depends: base         >= 4   && < 5-               , transformers >= 0.2 && < 0.3-  ghc-options: -Wall--  exposed-modules:-     Control.Failure--source-repository head-  type:     git-  location: git://github.com/snoyberg/failure.git+name: failure
+version: 0.1.2
+Cabal-Version:  >= 1.6
+build-type: Simple
+license: BSD3
+author: Pepe Iborra, Michael Snoyman, Nicolas Pouillard
+maintainer: pepeiborra@gmail.com
+homepage: http://www.haskell.org/haskellwiki/Failure
+description: A simple type class for success/failure computations.
+synopsis: A simple type class for success/failure computations.
+category: Control, Monads, Failure
+stability: stable
+
+flag base43
+
+Library
+  buildable: True
+  if flag(base43)
+    build-depends: base >= 4.3 && < 5
+  else
+    build-depends: base >= 4 && < 4.3
+                 , transformers >= 0.2 && < 0.3
+  ghc-options: -Wall
+
+  exposed-modules:
+     Control.Failure
+
+source-repository head
+  type:     git
+  location: git://github.com/snoyberg/failure.git