MonadFail: Make backwards-compatible

src/compiler/GF/Infra/CheckM.hs

@@ -32,6 +32,7 @@ import System.FilePath(makeRelative)
 import Control.Parallel.Strategies(parList,rseq,using)
 import Control.Monad(liftM,ap)
 import Control.Applicative(Applicative(..))
+import qualified Control.Monad.Fail as Fail
 
 type Message = Doc
 type Error   = Message
@@ -53,7 +54,7 @@ instance Monad Check where
                  (ws,Success x) -> unCheck (g x) {-ctxt-} ws
                  (ws,Fail msg)  -> (ws,Fail msg)
 
-instance MonadFail Check where
+instance Fail.MonadFail Check where
   fail = raise
 
 instance Applicative Check where

src/compiler/GF/Infra/Option.hs

@@ -44,6 +44,7 @@ import Data.Set (Set)
 import qualified Data.Set as Set
 
 import PGF.Internal(Literal(..))
+import qualified Control.Monad.Fail as Fail
 
 usageHeader :: String
 usageHeader = unlines 
@@ -547,7 +548,7 @@ lookupShow xs z = fromMaybe "lookupShow" $ lookup z [(y,x) | (x,y) <- xs]
 lookupReadsPrec :: [(String,a)] -> Int -> ReadS a
 lookupReadsPrec xs _ s = [(z,rest) | (x,rest) <- lex s, (y,z) <- xs, y == x]
 
-onOff :: MonadFail m => (Bool -> m a) -> Bool -> ArgDescr (m a)
+onOff :: Fail.MonadFail m => (Bool -> m a) -> Bool -> ArgDescr (m a)
 onOff f def = OptArg g "[on,off]"
   where g ma = maybe (return def) readOnOff ma >>= f
         readOnOff x = case map toLower x of
@@ -555,7 +556,7 @@ onOff f def = OptArg g "[on,off]"
                         "off" -> return False
                         _     -> fail $ "Expected [on,off], got: " ++ show x
 
-readOutputFormat :: MonadFail m => String -> m OutputFormat
+readOutputFormat :: Fail.MonadFail m => String -> m OutputFormat
 readOutputFormat s = 
     maybe (fail $ "Unknown output format: " ++ show s) return $ lookup s outputFormats
 

src/compiler/GF/Infra/SIO.hs

@@ -42,6 +42,7 @@ import qualified GF.Command.Importing as GF(importGrammar, importSource)
 #ifdef C_RUNTIME
 import qualified PGF2
 #endif
+import qualified Control.Monad.Fail as Fail
 
 -- * The SIO monad
 
@@ -58,7 +59,7 @@ instance Monad SIO where
   return x = SIO (const (return x))
   SIO m1 >>= xm2 = SIO $ \ h -> m1 h >>= \ x -> unS (xm2 x) h
 
-instance MonadFail SIO where
+instance Fail.MonadFail SIO where
   fail = liftSIO . fail
 
 instance Output SIO where