CodeGenMonad: add Functor instance

[harpy.git] / Harpy / CodeGenMonad.hs

diff --git a/Harpy/CodeGenMonad.hs b/Harpy/CodeGenMonad.hs
index c716b70498cd48acacfa37cdb62b12fc8917d07d..94d68a1182977a6ba3823fb9dc030c5c0b69f9cd 100644 (file)
--- a/Harpy/CodeGenMonad.hs
+++ b/Harpy/CodeGenMonad.hs
@@ -173,6 +173,9 @@ instance Monad (CodeGen e s) where
     fail err = cgFail err
     m >>= k = cgBind m k
 
+instance Functor (CodeGen e s) where
+  fmap = liftM
+
 cgReturn :: a -> CodeGen e s a
 cgReturn x = CodeGen (\_env state -> return (state, Right x))