MonadFail: Make backwards-compatible

gf.cabal

@@ -82,6 +82,7 @@ Library
                  pretty,
                  mtl,
                  exceptions,
+                 fail,
                  ghc-prim
   hs-source-dirs: src/runtime/haskell
 

src/compiler/GF/Command/Commands2.hs

@@ -25,7 +25,7 @@ data PGFEnv = Env {pgf::Maybe PGF,concs::Map.Map ConcName Concr}
 pgfEnv pgf = Env (Just pgf) (languages pgf)
 emptyPGFEnv = Env Nothing Map.empty
 
-class (MonadFail m,MonadSIO m) => HasPGFEnv m where getPGFEnv :: m PGFEnv
+class (Fail.MonadFail m,MonadSIO m) => HasPGFEnv m where getPGFEnv :: m PGFEnv
 
 instance (Monad m,HasPGFEnv m) => TypeCheckArg m where
   typeCheckArg e = do env <- getPGFEnv

src/compiler/GF/Compile/GeneratePMCFG.hs

@@ -41,6 +41,7 @@ import Control.Monad
 import Control.Monad.Identity
 --import Control.Exception
 --import Debug.Trace(trace)
+import qualified Control.Monad.Fail as Fail
 
 ----------------------------------------------------------------------
 -- main conversion function
@@ -196,7 +197,7 @@ newtype CnvMonad a = CM {unCM :: SourceGrammar
                               -> ([ProtoFCat],[Symbol])
                               -> Branch b}
 
-instance MonadFail CnvMonad where
+instance Fail.MonadFail CnvMonad where
   fail = bug
 
 instance Applicative CnvMonad where

src/compiler/GF/Compile/TypeCheck/ConcreteNew.hs

@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP #-}
 module GF.Compile.TypeCheck.ConcreteNew( checkLType, inferLType ) where
 
 -- The code here is based on the paper:
@@ -19,6 +20,7 @@ import GF.Text.Pretty
 import Data.List (nub, (\\), tails)
 import qualified Data.IntMap as IntMap
 import Data.Maybe(fromMaybe,isNothing)
+import qualified Control.Monad.Fail as Fail
 
 checkLType :: GlobalEnv -> Term -> Type -> Check (Term, Type)
 checkLType ge t ty = runTcM $ do
@@ -647,7 +649,12 @@ instance Monad TcM where
                                 TcOk x ms msgs -> unTcM (g x) ms msgs
                                 TcFail    msgs -> TcFail msgs)
 
-instance MonadFail TcM where
+#if !(MIN_VERSION_base(4,13,0))
+  -- Monad(fail) will be removed in GHC 8.8+
+  fail = Fail.fail
+#endif
+
+instance Fail.MonadFail TcM where
   fail     = tcError . pp
 
 

src/compiler/GF/Compile/Update.hs

@@ -27,9 +27,10 @@ import Data.List
 import qualified Data.Map as Map
 import Control.Monad
 import GF.Text.Pretty
+import qualified Control.Monad.Fail as Fail
 
 -- | combine a list of definitions into a balanced binary search tree
-buildAnyTree :: MonadFail m => ModuleName -> [(Ident,Info)] -> m (Map.Map Ident Info)
+buildAnyTree :: Fail.MonadFail m => ModuleName -> [(Ident,Info)] -> m (Map.Map Ident Info)
 buildAnyTree m = go Map.empty
   where
     go map []         = return map

src/compiler/GF/CompileInParallel.hs

@@ -20,6 +20,8 @@ import GF.Infra.Ident(moduleNameS)
 import GF.Text.Pretty
 import GF.System.Console(TermColors(..),getTermColors)
 import qualified Data.ByteString.Lazy as BS
+-- Control.Monad.Fail import will become redundant in GHC 8.8+
+import qualified Control.Monad.Fail as Fail
 
 -- | Compile the given grammar files and everything they depend on,
 -- like 'batchCompile'. This function compiles modules in parallel.
@@ -256,7 +258,7 @@ instance Output m => Output (CollectOutput m) where
   putStrLnE s = CO (return (putStrLnE s,()))
   putStrE   s = CO (return (putStrE s,()))
 
-instance MonadFail m => MonadFail (CollectOutput m) where
+instance Fail.MonadFail m => Fail.MonadFail (CollectOutput m) where
   fail = CO . fail
 
 instance ErrorMonad m => ErrorMonad (CollectOutput m) where

src/compiler/GF/CompileOne.hs

@@ -30,12 +30,13 @@ import qualified Data.Map as Map
 import GF.Text.Pretty(render,(<+>),($$)) --Doc,
 import GF.System.Console(TermColors(..),getTermColors)
 import Control.Monad((<=<))
+import qualified Control.Monad.Fail as Fail
 
 type OneOutput = (Maybe FullPath,CompiledModule)
 type CompiledModule = Module
 
 compileOne, reuseGFO, useTheSource ::
-    (Output m,ErrorMonad m,MonadIO m, MonadFail m) =>
+    (Output m,ErrorMonad m,MonadIO m, Fail.MonadFail m) =>
     Options -> Grammar -> FullPath -> m OneOutput
 
 -- | Compile a given source file (or just load a .gfo file),

src/compiler/GF/Data/BacktrackM.hs

@@ -13,6 +13,7 @@
 -----------------------------------------------------------------------------
 
 {-# LANGUAGE Rank2Types, MultiParamTypeClasses, FlexibleInstances #-}
+{-# LANGUAGE CPP #-}
 module GF.Data.BacktrackM (
                     -- * the backtracking state monad
 		    BacktrackM,
@@ -32,6 +33,7 @@ import Data.List
 import Control.Applicative
 import Control.Monad
 import Control.Monad.State.Class
+import qualified Control.Monad.Fail as Fail
 
 ----------------------------------------------------------------------
 -- Combining endomorphisms and continuations
@@ -70,7 +72,12 @@ instance Monad (BacktrackM s) where
     BM m >>= k = BM (\c s b -> m (\a s b -> unBM (k a) c s b) s b)
 	where unBM (BM m) = m
 
-instance MonadFail (BacktrackM s) where
+#if !(MIN_VERSION_base(4,13,0))
+  -- Monad(fail) will be removed in GHC 8.8+
+  fail = Fail.fail
+#endif
+
+instance Fail.MonadFail (BacktrackM s) where
     fail _ = mzero
 
 instance Functor (BacktrackM s) where

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
 
 

src/compiler/GF/Data/Operations.hs

@@ -53,6 +53,7 @@ import Control.Monad (liftM,liftM2) --,ap
 
 import GF.Data.ErrM
 import GF.Data.Relation
+import qualified Control.Monad.Fail as Fail
 
 infixr 5 +++
 infixr 5 ++-
@@ -88,10 +89,10 @@ checkUnique ss = ["overloaded" +++ show s | s <- nub overloads] where
   overloaded s = length (filter (==s) ss) > 1
 
 -- | this is what happens when matching two values in the same module
-unifyMaybe :: (Eq a, MonadFail m) => Maybe a -> Maybe a -> m (Maybe a)
+unifyMaybe :: (Eq a, Fail.MonadFail m) => Maybe a -> Maybe a -> m (Maybe a)
 unifyMaybe = unifyMaybeBy id
 
-unifyMaybeBy :: (Eq b, MonadFail m) => (a->b) -> Maybe a -> Maybe a -> m (Maybe a)
+unifyMaybeBy :: (Eq b, Fail.MonadFail m) => (a->b) -> Maybe a -> Maybe a -> m (Maybe a)
 unifyMaybeBy f (Just p1) (Just p2)
   | f p1==f p2                     = return (Just p1)
   | otherwise                      = fail ""

src/compiler/GF/Grammar/Lexer.x

@@ -19,6 +19,7 @@ import qualified Data.Map as Map
 import Data.Word(Word8)
 import Data.Char(readLitChar)
 --import Debug.Trace(trace)
+import qualified Control.Monad.Fail as Fail
 }
 
 
@@ -285,7 +286,7 @@ instance Monad P where
                              PFailed posn err -> PFailed posn err
 
 
-instance MonadFail P where
+instance Fail.MonadFail P where
   fail msg    = P $ \(_,AI posn _ _) -> PFailed posn msg
 
 

src/compiler/GF/Grammar/Macros.hs

@@ -32,6 +32,7 @@ import Control.Monad (liftM, liftM2, liftM3)
 import Data.List (sortBy,nub)
 import Data.Monoid
 import GF.Text.Pretty(render,(<+>),hsep,fsep)
+import qualified Control.Monad.Fail as Fail
 
 -- ** Functions for constructing and analysing source code terms.
 
@@ -237,7 +238,7 @@ isPredefConstant t = case t of
   Q (mod,_) | mod == cPredef || mod == cPredefAbs -> True
   _                                               -> False
 
-checkPredefError :: MonadFail m => Term -> m Term
+checkPredefError :: Fail.MonadFail m => Term -> m Term
 checkPredefError t =
     case t of
       Error s -> fail ("Error: "++s)

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