Add MonadExcept IdentityT instance

ghc · Apr 3, 2017 · cfaeafa · cfaeafa
1 parent 91f6afd
commit cfaeafa
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Showing 2 changed files with 3 additions and 1 deletion.
diff --git a/System/Console/Haskeline/MonadException.hs b/System/Console/Haskeline/MonadException.hs
@@ -33,6 +33,7 @@ import Prelude hiding (catch)
 #endif
 import Control.Monad(liftM, join)
 import Control.Monad.IO.Class
+import Control.Monad.Trans.Identity
 import Control.Monad.Trans.Reader
 import Control.Monad.Trans.State.Strict
 import Control.Monad.Trans.Error
@@ -179,4 +180,4 @@ instance (Monoid w, MonadException m) => MonadException (RWST r w s m) where
                                     . run . (\m -> runRWST m r s))
                     in fmap (\m -> runRWST m r s) $ f run'
 
-
+deriving instance MonadException m => MonadException (IdentityT m)
diff --git a/haskeline.cabal b/haskeline.cabal
@@ -52,6 +52,7 @@ Library
                 TypeSynonymInstances
                 FlexibleContexts, ExistentialQuantification
                 ScopedTypeVariables, GeneralizedNewtypeDeriving
+                StandaloneDeriving
                 MultiParamTypeClasses, OverlappingInstances
                 UndecidableInstances
                 ScopedTypeVariables, CPP, DeriveDataTypeable,