Merge pull request #186 from endgame/monadfail

MonadFail support
gregwebs · Jun 27, 2019 · 1b6643a · 1b6643a
2 parents ba71d21 + 5093c26
commit 1b6643a
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Showing 2 changed files with 5 additions and 1 deletion.
diff --git a/shelly.cabal b/shelly.cabal
@@ -143,6 +143,9 @@ Test-Suite shelly-testsuite
     enclosed-exceptions,
     exceptions
 
+  if impl(ghc < 8.0)
+    build-depends:       fail >= 4.9 && < 4.10
+
   extensions:
     CPP
 

diff --git a/src/Shelly/Base.hs b/src/Shelly/Base.hs
@@ -44,6 +44,7 @@ import System.IO ( Handle, hFlush, stderr, stdout )
 import Control.Monad (when, (>=>),
          liftM
        )
+import Control.Monad.Fail (MonadFail)
 import Control.Monad.Base
 import Control.Monad.Trans.Control
 import Control.Applicative (Applicative, (<$>))
@@ -71,7 +72,7 @@ type ShIO a = Sh a
 
 newtype Sh a = Sh {
       unSh :: ReaderT (IORef State) IO a
-  } deriving (Applicative, Monad, MonadIO, MonadReader (IORef State), Functor, Catch.MonadMask)
+  } deriving (Applicative, Monad, MonadFail, MonadIO, MonadReader (IORef State), Functor, Catch.MonadMask)
 
 instance MonadBase IO Sh where
     liftBase = Sh . ReaderT . const