diff --git a/Control/Monad/IO/Class.hs b/Control/Monad/IO/Class.hs --- a/Control/Monad/IO/Class.hs +++ b/Control/Monad/IO/Class.hs @@ -3,9 +3,9 @@ -- Module : Control.Monad.IO.Class -- Copyright : (c) Andy Gill 2001, -- (c) Oregon Graduate Institute of Science and Technology, 2001 --- License : BSD-style (see the file libraries/base/LICENSE) +-- License : BSD-style (see the file LICENSE) -- --- Maintainer : libraries@haskell.org +-- Maintainer : ross@soi.city.ac.uk -- Stability : experimental -- Portability : portable -- diff --git a/Control/Monad/Trans/Class.hs b/Control/Monad/Trans/Class.hs --- a/Control/Monad/Trans/Class.hs +++ b/Control/Monad/Trans/Class.hs @@ -3,9 +3,9 @@ -- Module : Control.Monad.Trans.Class -- Copyright : (c) Andy Gill 2001, -- (c) Oregon Graduate Institute of Science and Technology, 2001 --- License : BSD-style (see the file libraries/base/LICENSE) +-- License : BSD-style (see the file LICENSE) -- --- Maintainer : libraries@haskell.org +-- Maintainer : ross@soi.city.ac.uk -- Stability : experimental -- Portability : portable -- diff --git a/Control/Monad/Trans/Cont.hs b/Control/Monad/Trans/Cont.hs --- a/Control/Monad/Trans/Cont.hs +++ b/Control/Monad/Trans/Cont.hs @@ -2,9 +2,9 @@ -- | -- Module : Control.Monad.Trans.Cont -- Copyright : (c) The University of Glasgow 2001 --- License : BSD-style (see the file libraries/base/LICENSE) +-- License : BSD-style (see the file LICENSE) -- --- Maintainer : libraries@haskell.org +-- Maintainer : ross@soi.city.ac.uk -- Stability : experimental -- Portability : portable -- diff --git a/Control/Monad/Trans/Error.hs b/Control/Monad/Trans/Error.hs --- a/Control/Monad/Trans/Error.hs +++ b/Control/Monad/Trans/Error.hs @@ -1,24 +1,27 @@ -{- | -Module : Control.Monad.Trans.Error -Copyright : (c) Michael Weber 2001, - (c) Jeff Newbern 2003-2006, - (c) Andriy Palamarchuk 2006 -License : BSD-style (see the file libraries/base/LICENSE) - -Maintainer : libraries@haskell.org -Stability : experimental -Portability : portable - -This monad transformer adds the ability to fail or throw exceptions -to a monad. - -A sequence of actions succeeds, producing a value, only if all the actions -in the sequence are successful. If one fails with an error, the rest -of the sequence is skipped and the composite action fails with that error. - -If the value of the error is not required, the variant in -"Control.Monad.Trans.Maybe" may be used instead. --} +{-# LANGUAGE CPP #-} +----------------------------------------------------------------------------- +-- | +-- Module : Control.Monad.Trans.Error +-- Copyright : (c) Michael Weber 2001, +-- (c) Jeff Newbern 2003-2006, +-- (c) Andriy Palamarchuk 2006 +-- License : BSD-style (see the file LICENSE) +-- +-- Maintainer : ross@soi.city.ac.uk +-- Stability : experimental +-- Portability : portable +-- +-- This monad transformer adds the ability to fail or throw exceptions +-- to a monad. +-- +-- A sequence of actions succeeds, producing a value, only if all the +-- actions in the sequence are successful. If one fails with an error, +-- the rest of the sequence is skipped and the composite action fails +-- with that error. +-- +-- If the value of the error is not required, the variant in +-- "Control.Monad.Trans.Maybe" may be used instead. +----------------------------------------------------------------------------- module Control.Monad.Trans.Error ( -- * The ErrorT monad transformer @@ -82,34 +85,39 @@ -- --------------------------------------------------------------------------- -- Our parameterizable error monad +#if !(MIN_VERSION_base(4,2,1)) + +-- These instances are in base-4.3 + instance Applicative (Either e) where pure = Right Left e <*> _ = Left e Right f <*> r = fmap f r -instance (Error e) => Alternative (Either e) where - empty = Left noMsg - Left _ <|> n = n - m <|> _ = m - -instance (Error e) => Monad (Either e) where +instance Monad (Either e) where return = Right Left l >>= _ = Left l Right r >>= k = k r - fail msg = Left (strMsg msg) -instance (Error e) => MonadPlus (Either e) where - mzero = Left noMsg - Left _ `mplus` n = n - m `mplus` _ = m - -instance (Error e) => MonadFix (Either e) where +instance MonadFix (Either e) where mfix f = let a = f $ case a of Right r -> r _ -> error "empty mfix argument" in a +#endif /* base to 4.2.0.x */ + +instance (Error e) => Alternative (Either e) where + empty = Left noMsg + Left _ <|> n = n + m <|> _ = m + +instance (Error e) => MonadPlus (Either e) where + mzero = Left noMsg + Left _ `mplus` n = n + m `mplus` _ = m + -- | The error monad transformer. It can be used to add error handling -- to other monads. -- @@ -223,12 +231,15 @@ {- $examples -> -- wraps IO action that can throw an error e +Wrapping an IO action that can throw an error @e@: + > type ErrorWithIO e a = ErrorT e IO a > ==> ErrorT (IO (Either e a)) -> -> -- IO monad wrapped in StateT inside of ErrorT + +An IO monad wrapped in @StateT@ inside of @ErrorT@: + > type ErrorAndStateWithIO e s a = ErrorT e (StateT s IO) a > ==> ErrorT (StateT s IO (Either e a)) > ==> ErrorT (StateT (s -> IO (Either e a,s))) + -} diff --git a/Control/Monad/Trans/Identity.hs b/Control/Monad/Trans/Identity.hs --- a/Control/Monad/Trans/Identity.hs +++ b/Control/Monad/Trans/Identity.hs @@ -4,7 +4,7 @@ -- Copyright : (c) 2007 Magnus Therning -- License : BSD-style (see the file LICENSE) -- --- Maintainer : libraries@haskell.org +-- Maintainer : ross@soi.city.ac.uk -- Stability : experimental -- Portability : portable -- diff --git a/Control/Monad/Trans/List.hs b/Control/Monad/Trans/List.hs --- a/Control/Monad/Trans/List.hs +++ b/Control/Monad/Trans/List.hs @@ -3,9 +3,9 @@ -- Module : Control.Monad.Trans.List -- Copyright : (c) Andy Gill 2001, -- (c) Oregon Graduate Institute of Science and Technology, 2001 --- License : BSD-style (see the file libraries/base/LICENSE) +-- License : BSD-style (see the file LICENSE) -- --- Maintainer : libraries@haskell.org +-- Maintainer : ross@soi.city.ac.uk -- Stability : experimental -- Portability : portable -- diff --git a/Control/Monad/Trans/Maybe.hs b/Control/Monad/Trans/Maybe.hs --- a/Control/Monad/Trans/Maybe.hs +++ b/Control/Monad/Trans/Maybe.hs @@ -4,7 +4,7 @@ -- Copyright : (c) 2007 Yitzak Gale, Eric Kidd -- License : BSD-style (see the file LICENSE) -- --- Maintainer : libraries@haskell.org +-- Maintainer : ross@soi.city.ac.uk -- Stability : experimental -- Portability : portable -- diff --git a/Control/Monad/Trans/RWS.hs b/Control/Monad/Trans/RWS.hs --- a/Control/Monad/Trans/RWS.hs +++ b/Control/Monad/Trans/RWS.hs @@ -3,9 +3,9 @@ -- Module : Control.Monad.Trans.RWS -- Copyright : (c) Andy Gill 2001, -- (c) Oregon Graduate Institute of Science and Technology, 2001 --- License : BSD-style (see the file libraries/base/LICENSE) +-- License : BSD-style (see the file LICENSE) -- --- Maintainer : libraries@haskell.org +-- Maintainer : ross@soi.city.ac.uk -- Stability : experimental -- Portability : portable -- diff --git a/Control/Monad/Trans/RWS/Lazy.hs b/Control/Monad/Trans/RWS/Lazy.hs --- a/Control/Monad/Trans/RWS/Lazy.hs +++ b/Control/Monad/Trans/RWS/Lazy.hs @@ -3,9 +3,9 @@ -- Module : Control.Monad.Trans.RWS.Lazy -- Copyright : (c) Andy Gill 2001, -- (c) Oregon Graduate Institute of Science and Technology, 2001 --- License : BSD-style (see the file libraries/base/LICENSE) +-- License : BSD-style (see the file LICENSE) -- --- Maintainer : libraries@haskell.org +-- Maintainer : ross@soi.city.ac.uk -- Stability : experimental -- Portability : portable -- diff --git a/Control/Monad/Trans/RWS/Strict.hs b/Control/Monad/Trans/RWS/Strict.hs --- a/Control/Monad/Trans/RWS/Strict.hs +++ b/Control/Monad/Trans/RWS/Strict.hs @@ -3,9 +3,9 @@ -- Module : Control.Monad.Trans.RWS.Strict -- Copyright : (c) Andy Gill 2001, -- (c) Oregon Graduate Institute of Science and Technology, 2001 --- License : BSD-style (see the file libraries/base/LICENSE) +-- License : BSD-style (see the file LICENSE) -- --- Maintainer : libraries@haskell.org +-- Maintainer : ross@soi.city.ac.uk -- Stability : experimental -- Portability : portable -- diff --git a/Control/Monad/Trans/Reader.hs b/Control/Monad/Trans/Reader.hs --- a/Control/Monad/Trans/Reader.hs +++ b/Control/Monad/Trans/Reader.hs @@ -5,7 +5,7 @@ -- (c) Oregon Graduate Institute of Science and Technology, 2001 -- License : BSD-style (see the file LICENSE) -- --- Maintainer : libraries@haskell.org +-- Maintainer : ross@soi.city.ac.uk -- Stability : experimental -- Portability : portable -- diff --git a/Control/Monad/Trans/State.hs b/Control/Monad/Trans/State.hs --- a/Control/Monad/Trans/State.hs +++ b/Control/Monad/Trans/State.hs @@ -3,9 +3,9 @@ -- Module : Control.Monad.Trans.State -- Copyright : (c) Andy Gill 2001, -- (c) Oregon Graduate Institute of Science and Technology, 2001 --- License : BSD-style (see the file libraries/base/LICENSE) +-- License : BSD-style (see the file LICENSE) -- --- Maintainer : libraries@haskell.org +-- Maintainer : ross@soi.city.ac.uk -- Stability : experimental -- Portability : portable -- diff --git a/Control/Monad/Trans/State/Lazy.hs b/Control/Monad/Trans/State/Lazy.hs --- a/Control/Monad/Trans/State/Lazy.hs +++ b/Control/Monad/Trans/State/Lazy.hs @@ -3,9 +3,9 @@ -- Module : Control.Monad.Trans.State.Lazy -- Copyright : (c) Andy Gill 2001, -- (c) Oregon Graduate Institute of Science and Technology, 2001 --- License : BSD-style (see the file libraries/base/LICENSE) +-- License : BSD-style (see the file LICENSE) -- --- Maintainer : libraries@haskell.org +-- Maintainer : ross@soi.city.ac.uk -- Stability : experimental -- Portability : portable -- diff --git a/Control/Monad/Trans/State/Strict.hs b/Control/Monad/Trans/State/Strict.hs --- a/Control/Monad/Trans/State/Strict.hs +++ b/Control/Monad/Trans/State/Strict.hs @@ -3,9 +3,9 @@ -- Module : Control.Monad.Trans.State.Strict -- Copyright : (c) Andy Gill 2001, -- (c) Oregon Graduate Institute of Science and Technology, 2001 --- License : BSD-style (see the file libraries/base/LICENSE) +-- License : BSD-style (see the file LICENSE) -- --- Maintainer : libraries@haskell.org +-- Maintainer : ross@soi.city.ac.uk -- Stability : experimental -- Portability : portable -- diff --git a/Control/Monad/Trans/Writer.hs b/Control/Monad/Trans/Writer.hs --- a/Control/Monad/Trans/Writer.hs +++ b/Control/Monad/Trans/Writer.hs @@ -3,9 +3,9 @@ -- Module : Control.Monad.Trans.Writer -- Copyright : (c) Andy Gill 2001, -- (c) Oregon Graduate Institute of Science and Technology, 2001 --- License : BSD-style (see the file libraries/base/LICENSE) +-- License : BSD-style (see the file LICENSE) -- --- Maintainer : libraries@haskell.org +-- Maintainer : ross@soi.city.ac.uk -- Stability : experimental -- Portability : portable -- diff --git a/Control/Monad/Trans/Writer/Lazy.hs b/Control/Monad/Trans/Writer/Lazy.hs --- a/Control/Monad/Trans/Writer/Lazy.hs +++ b/Control/Monad/Trans/Writer/Lazy.hs @@ -3,9 +3,9 @@ -- Module : Control.Monad.Trans.Writer.Lazy -- Copyright : (c) Andy Gill 2001, -- (c) Oregon Graduate Institute of Science and Technology, 2001 --- License : BSD-style (see the file libraries/base/LICENSE) +-- License : BSD-style (see the file LICENSE) -- --- Maintainer : libraries@haskell.org +-- Maintainer : ross@soi.city.ac.uk -- Stability : experimental -- Portability : portable -- diff --git a/Control/Monad/Trans/Writer/Strict.hs b/Control/Monad/Trans/Writer/Strict.hs --- a/Control/Monad/Trans/Writer/Strict.hs +++ b/Control/Monad/Trans/Writer/Strict.hs @@ -3,9 +3,9 @@ -- 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 libraries/base/LICENSE) +-- License : BSD-style (see the file LICENSE) -- --- Maintainer : libraries@haskell.org +-- Maintainer : ross@soi.city.ac.uk -- Stability : experimental -- Portability : portable -- diff --git a/Data/Functor/Compose.hs b/Data/Functor/Compose.hs --- a/Data/Functor/Compose.hs +++ b/Data/Functor/Compose.hs @@ -1,9 +1,9 @@ -- | -- Module : Data.Functor.Compose -- Copyright : (c) Ross Paterson 2010 --- License : BSD-style (see the file libraries/base/LICENSE) +-- License : BSD-style (see the file LICENSE) -- --- Maintainer : libraries@haskell.org +-- Maintainer : ross@soi.city.ac.uk -- Stability : experimental -- Portability : portable -- diff --git a/Data/Functor/Constant.hs b/Data/Functor/Constant.hs --- a/Data/Functor/Constant.hs +++ b/Data/Functor/Constant.hs @@ -1,9 +1,9 @@ -- | -- Module : Data.Functor.Constant -- Copyright : (c) Ross Paterson 2010 --- License : BSD-style (see the file libraries/base/LICENSE) +-- License : BSD-style (see the file LICENSE) -- --- Maintainer : libraries@haskell.org +-- Maintainer : ross@soi.city.ac.uk -- Stability : experimental -- Portability : portable -- diff --git a/Data/Functor/Identity.hs b/Data/Functor/Identity.hs --- a/Data/Functor/Identity.hs +++ b/Data/Functor/Identity.hs @@ -2,9 +2,9 @@ -- Module : Data.Functor.Identity -- Copyright : (c) Andy Gill 2001, -- (c) Oregon Graduate Institute of Science and Technology 2001 --- License : BSD-style (see the file libraries/base/LICENSE) +-- License : BSD-style (see the file LICENSE) -- --- Maintainer : libraries@haskell.org +-- Maintainer : ross@soi.city.ac.uk -- Stability : experimental -- Portability : portable -- diff --git a/Data/Functor/Product.hs b/Data/Functor/Product.hs --- a/Data/Functor/Product.hs +++ b/Data/Functor/Product.hs @@ -1,9 +1,9 @@ -- | -- Module : Data.Functor.Product -- Copyright : (c) Ross Paterson 2010 --- License : BSD-style (see the file libraries/base/LICENSE) +-- License : BSD-style (see the file LICENSE) -- --- Maintainer : libraries@haskell.org +-- Maintainer : ross@soi.city.ac.uk -- Stability : experimental -- Portability : portable -- diff --git a/transformers.cabal b/transformers.cabal --- a/transformers.cabal +++ b/transformers.cabal @@ -1,5 +1,5 @@ name: transformers -version: 0.2.1.0 +version: 0.2.2.0 license: BSD3 license-file: LICENSE author: Andy Gill, Ross Paterson @@ -18,7 +18,7 @@ @monads-tf@ packages, which automatically lift operations introduced by monad transformers through other transformers. build-type: Simple -cabal-version: >= 1.2 +cabal-version: >= 1.5.5 flag ApplicativeInBase description: Choose the newer base package, including Applicative and other