diff --git a/CHANGELOG.md b/CHANGELOG.md --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -1,3 +1,17 @@ +### 0.2.0.3 +* A specific build with no flags explicitly enabled, intended for use with the latest version of `mtl`. This is a workaround for `cabal` backtracker bugs. + +### 0.2.0.2 +* A specific build with the `-ftwo-point-two` flag explicitly enabled. This is a workaround for `cabal` backtracker bugs. + +### 0.2.0.1 +* A specific build with the `-ftwo-point-one` flag explicitly enabled. This is a workaround for `cabal` backtracker bugs. + +# 0.2 +* Require use of `transformers-compat-0.4` or greater when building with `mtl-2.1.3.1` or earlier. `transformers-compat-0.4.0.*` adds the missing `ExceptT` instances, which means that `mtl-compat`'s only purpose is to backport the `Control.Monad.Except` module for those who want an `mtl`-style import for `ExceptT` and/or `MonadError`. + + I would recommend just using `Control.Monad.Trans.Except` from `transformers-compat-0.4.0.*` and `Control.Monad.Error.Class` instead, since they accomplish the same thing as `mtl-compat` without an extra dependency. + ## 0.1.1 * Allowed the `two-point-one` flag to toggle on/off automatically diff --git a/README.md b/README.md --- a/README.md +++ b/README.md @@ -1,2 +1,7 @@ -# `mtl-compat` -Orphan [`mtl`](http://hackage.haskell.org/package/mtl) instances for `ExceptT` from [`transformers-compat`](http://hackage.haskell.org/package/transformers-compat) +# `mtl-compat` [![Hackage version](https://img.shields.io/hackage/v/mtl-compat.svg?style=flat)](http://hackage.haskell.org/package/mtl-compat) [![Build Status](https://img.shields.io/travis/RyanGlScott/mtl-compat.svg?style=flat)](https://travis-ci.org/RyanGlScott/mtl-compat) + +This package backports the `Control.Monad.Except` module from `mtl` (if using `mtl-2.2.0.1` or earlier), which reexports the `ExceptT` monad transformer and the `MonadError` class. + +This package should only be used if there is a need to use the `Control.Monad.Except` module specifically. If you just want `mtl` class instances for `ExceptT`, use `transformers-compat` instead, since `mtl-compat` does nothing but reexport the instances from that package. + +Note that unlike how `mtl-2.2` or later works, the `Control.Monad.Except` module defined in this package exports all of `ExceptT`'s monad class instances. Therefore, you may have to declare `import Control.Monad.Except ()` at the top of your file to get all of the `ExceptT` instances in scope. diff --git a/mtl-compat.cabal b/mtl-compat.cabal --- a/mtl-compat.cabal +++ b/mtl-compat.cabal @@ -1,11 +1,16 @@ name: mtl-compat -version: 0.1.1 -synopsis: Orphan mtl instances for ExceptT from transformers-compat -description: This package backports the "Control.Monad.Except" module (if - using @mtl-2.2.0.1@ or earlier) and monad class instances for - @ExceptT@ from @transformers-compat@ (if using @mtl-2.1.3.1@ - or earlier). +version: 0.2.0.4 +synopsis: Backported Control.Monad.Except module from mtl +description: This package backports the "Control.Monad.Except" module from + @mtl@ (if using @mtl-2.2.0.1@ or earlier), which reexports the + @ExceptT@ monad transformer and the @MonadError@ class. . + This package should only be used if there is a need to use the + @Control.Monad.Except@ module specifically. If you just want + the @mtl@ class instances for @ExceptT@, use + @transformers-compat@ instead, since @mtl-compat@ does nothing + but reexport the instances from that package. + . Note that unlike how @mtl-2.2@ or later works, the "Control.Monad.Except" module defined in this package exports all of @ExceptT@'s monad class instances. Therefore, you may @@ -30,15 +35,15 @@ flag two-point-one default: False - manual: False - description: Use mtl-2.1.3.1 or earlier with transformers-compat. - This should toggle on/off automatically. + manual: True + description: Use mtl-2.1.3.1 or earlier with transformers-compat. This + will cause this package to export the Control.Monad.Except module. flag two-point-two default: False manual: True - description: Use mtl-2.2.0.1. This is probably not what you want, so - this must be selected manually. + description: Use mtl-2.2.0.1 with transformers. This will cause this + package to export the Control.Monad.Except module. library build-depends: base >= 4.3 && < 5 @@ -49,7 +54,7 @@ if flag(two-point-one) build-depends: mtl >= 2.0.1 && < 2.2 - , transformers-compat >= 0.3 && < 0.4 + , transformers-compat >= 0.4 && < 0.5 else if flag(two-point-two) build-depends: mtl >= 2.2.0.1 && < 2.2.1 diff --git a/src/Control/Monad/Except.hs b/src/Control/Monad/Except.hs --- a/src/Control/Monad/Except.hs +++ b/src/Control/Monad/Except.hs @@ -1,8 +1,4 @@ {-# LANGUAGE CPP #-} -#if !(MIN_VERSION_mtl(2,2,0)) -{-# LANGUAGE FlexibleInstances, MultiParamTypeClasses, UndecidableInstances #-} -{-# OPTIONS_GHC -fno-warn-orphans #-} -#endif {- | Module : Control.Monad.Error Copyright : (c) Michael Weber 2001, @@ -74,45 +70,12 @@ import Control.Monad.Instances () #endif -#if MIN_VERSION_mtl(2,2,0) +#if MIN_VERSION_mtl(2,2,0) && !(MIN_VERSION_mtl(2,2,1)) import Control.Monad.Cont.Class () import Control.Monad.RWS.Class () import Control.Monad.Reader.Class () import Control.Monad.State.Class () import Control.Monad.Writer.Class () -#else -import Control.Monad.Cont.Class (MonadCont(..)) -import Control.Monad.Reader.Class (MonadReader(..)) -import Control.Monad.RWS.Class (MonadRWS) -import Control.Monad.State.Class (MonadState(..)) -import Control.Monad.Writer.Class (MonadWriter(..)) -import Control.Monad.Trans.Except - ( liftCallCC, throwE, catchE, liftListen, liftPass ) - -instance MonadCont m => MonadCont (ExceptT e m) where - callCC = liftCallCC callCC - -instance Monad m => MonadError e (ExceptT e m) where - throwError = throwE - catchError = catchE - -instance MonadRWS r w s m => MonadRWS r w s (ExceptT e m) - -instance MonadReader r m => MonadReader r (ExceptT e m) where - ask = lift ask - local = mapExceptT . local - reader = lift . reader - -instance MonadState s m => MonadState s (ExceptT e m) where - get = lift get - put = lift . put - state = lift . state - -instance MonadWriter w m => MonadWriter w (ExceptT e m) where - writer = lift . writer - tell = lift . tell - listen = liftListen listen - pass = liftPass pass #endif {- $customErrorExample