MonadFail instance for GHC 8.6

alpheccar · Nov 30, 2018 · d0a0ba2 · d0a0ba2
1 parent 5a90137
commit d0a0ba2
Showing 1 changed file with 8 additions and 0 deletions.
diff --git a/Graphics/PDF/Draw.hs b/Graphics/PDF/Draw.hs
@@ -86,6 +86,9 @@ import Data.Maybe
 #if !MIN_VERSION_base(4,8,0)
 import Data.Monoid
 #endif
+#if MIN_VERSION_base(4,9,0)
+import qualified Control.Monad.Fail as Fail
+#endif
 
 import qualified Data.Map.Strict as M
 import qualified Data.IntMap as IM
@@ -186,6 +189,11 @@ instance Monad Draw where
                           unDraw (f a) env
     return x = Draw $ \_env -> return x
 
+#if MIN_VERSION_base(4,9,0)
+instance Fail.MonadFail Draw where
+    fail s = Draw $ \_ -> Fail.fail s
+#endif
+
 instance MonadReader DrawEnvironment Draw where
    ask       = Draw $ \env -> return (drawEnvironment env)
    local f m = Draw $ \env -> let drawenv' = f (drawEnvironment env)