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| author | Herbert Valerio Riedel <hvr@gnu.org> | 2016-01-01 01:45:08 +0100 |
|---|---|---|
| committer | Herbert Valerio Riedel <hvr@gnu.org> | 2016-01-01 01:55:16 +0100 |
| commit | dafeb51f266793a67e8ae18ae39a2e2e87943824 (patch) | |
| tree | f1ef3abd7fc655e6b8896a6841f0efd9a39a39fe /compiler/utils/MonadUtils.hs | |
| parent | 8afeaad919dc67643b4eff14efafb48b59039b2b (diff) | |
| download | haskell-dafeb51f266793a67e8ae18ae39a2e2e87943824.tar.gz | |
Canonicalise `MonadPlus` instances
This refactoring exploits the fact that since AMP, in most cases,
`instance MonadPlus` can be automatically derived from the respective
`Alternative` instance. This is because `MonadPlus`'s default method
implementations are fully defined in terms of `Alternative(empty, (<>))`.
Diffstat (limited to 'compiler/utils/MonadUtils.hs')
| -rw-r--r-- | compiler/utils/MonadUtils.hs | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/compiler/utils/MonadUtils.hs b/compiler/utils/MonadUtils.hs index 36eb574e78..af4f0253db 100644 --- a/compiler/utils/MonadUtils.hs +++ b/compiler/utils/MonadUtils.hs @@ -1,3 +1,4 @@ +{-# LANGUAGE CPP #-} -- | Utilities related to Monad and Applicative classes -- Mostly for backwards compatability. @@ -30,11 +31,12 @@ module MonadUtils import Maybes -import Control.Applicative import Control.Monad import Control.Monad.Fix import Control.Monad.IO.Class -import Prelude -- avoid redundant import warning due to AMP +#if __GLASGOW_HASKELL__ < 800 +import Control.Monad.Trans.Error () -- for orphan `instance MonadPlus IO` +#endif ------------------------------------------------------------------------------- -- Lift combinators |