remove unsafe instance for MonadIO

Author: jdegoes

src/Control/Monad/IO/Class.purs

@@ -1,16 +1,10 @@
 module Control.Monad.IO.Class where
   import Control.Category (id)
   import Control.Monad (class Monad)
-  import Control.Monad.Aff (Aff)
   import Control.Monad.IO (IO)
 
-  import Unsafe.Coerce (unsafeCoerce)
-
   class Monad m <= MonadIO m where
     liftIO :: forall a. IO a -> m a
 
   instance monadIOIO :: MonadIO IO where
     liftIO = id
-
-  instance monadIOAff :: MonadIO (Aff e) where
-    liftIO = unsafeCoerce