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| author | Andreas Källberg <anka.213@gmail.com> | 2020-09-05 20:23:07 +0200 |
|---|---|---|
| committer | Andreas Källberg <anka.213@gmail.com> | 2020-09-05 20:23:07 +0200 |
| commit | 7268253f5ae4b4883d28faa87b3e63295f04abfd (patch) | |
| tree | fb95bb40e3f8dece1deb018857b948a645003993 /src/compiler/GF/Data/ErrM.hs | |
| parent | 1234c715fc6fe19d0c9fce794e4dfedf190b8d18 (diff) | |
MonadFail: Make backwards-compatible
Diffstat (limited to 'src/compiler/GF/Data/ErrM.hs')
| -rw-r--r-- | src/compiler/GF/Data/ErrM.hs | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/src/compiler/GF/Data/ErrM.hs b/src/compiler/GF/Data/ErrM.hs index 5ea7f0734..288c61919 100644 --- a/src/compiler/GF/Data/ErrM.hs +++ b/src/compiler/GF/Data/ErrM.hs @@ -12,10 +12,12 @@ -- hack for BNFC generated files. AR 21/9/2003 ----------------------------------------------------------------------------- +{-# LANGUAGE CPP #-} module GF.Data.ErrM where import Control.Monad (MonadPlus(..),ap) import Control.Applicative +import qualified Control.Monad.Fail as Fail -- | Like 'Maybe' type with error msgs data Err a = Ok a | Bad String @@ -36,7 +38,12 @@ instance Monad Err where Ok a >>= f = f a Bad s >>= f = Bad s -instance MonadFail Err where +#if !(MIN_VERSION_base(4,13,0)) + -- Monad(fail) will be removed in GHC 8.8+ + fail = Fail.fail +#endif + +instance Fail.MonadFail Err where fail = Bad |