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| author | John J. Camilleri <john@johnjcamilleri.com> | 2020-09-14 22:42:37 +0200 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2020-09-14 22:42:37 +0200 |
| commit | 6c54e5b63cb563d780843a1970cba0718a5203f8 (patch) | |
| tree | ed6777f6cb20f9212fa29ce68fac7e22745c707c /src/compiler/GF/Data/ErrM.hs | |
| parent | bca0691cb028fe33ae1b77e71752d4e937490ff1 (diff) | |
| parent | 8bcdeedba01847325cc89378fed114bc0561bd4d (diff) | |
Merge pull request #71 from anka-213/fix-newer-cabal
Fix support for newer stackage snapshots
Diffstat (limited to 'src/compiler/GF/Data/ErrM.hs')
| -rw-r--r-- | src/compiler/GF/Data/ErrM.hs | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/src/compiler/GF/Data/ErrM.hs b/src/compiler/GF/Data/ErrM.hs index 033c1efac..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 @@ -33,10 +35,19 @@ fromErr a = err (const a) id instance Monad Err where return = Ok - fail = Bad Ok a >>= f = f a Bad s >>= f = Bad s +#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 + + + -- | added 2\/10\/2003 by PEB instance Functor Err where fmap f (Ok a) = Ok (f a) |