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-rw-r--r--src/tools/c/GFCC/ErrM.hs13
1 files changed, 12 insertions, 1 deletions
diff --git a/src/tools/c/GFCC/ErrM.hs b/src/tools/c/GFCC/ErrM.hs
index 820473ccd..78295d30e 100644
--- a/src/tools/c/GFCC/ErrM.hs
+++ b/src/tools/c/GFCC/ErrM.hs
@@ -4,6 +4,10 @@
-- This file comes with NO WARRANTY and may be used FOR ANY PURPOSE.
module GFCC.ErrM where
+-- Control.Monad.Fail import will become redundant in GHC 8.8+
+import qualified Control.Monad.Fail as Fail
+
+
-- the Error monad: like Maybe type with error msgs
data Err a = Ok a | Bad String
@@ -11,6 +15,13 @@ data Err a = Ok a | Bad String
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))
+ fail = Bad
+#endif
+
+instance Fail.MonadFail Err where
+ fail = Bad
+