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Diffstat (limited to 'src/GF/Source/ErrM.hs')
| -rw-r--r-- | src/GF/Source/ErrM.hs | 26 |
1 files changed, 0 insertions, 26 deletions
diff --git a/src/GF/Source/ErrM.hs b/src/GF/Source/ErrM.hs deleted file mode 100644 index 63840758e..000000000 --- a/src/GF/Source/ErrM.hs +++ /dev/null @@ -1,26 +0,0 @@ --- BNF Converter: Error Monad --- Copyright (C) 2004 Author: Aarne Ranta - --- This file comes with NO WARRANTY and may be used FOR ANY PURPOSE. -module GF.Source.ErrM where - --- the Error monad: like Maybe type with error msgs - -import Control.Monad (MonadPlus(..), liftM) - -data Err a = Ok a | Bad String - deriving (Read, Show, Eq, Ord) - -instance Monad Err where - return = Ok - fail = Bad - Ok a >>= f = f a - Bad s >>= f = Bad s - -instance Functor Err where - fmap = liftM - -instance MonadPlus Err where - mzero = Bad "Err.mzero" - mplus (Bad _) y = y - mplus x _ = x |
