[Haskell-cafe] type families and type signatures

Hi, The following program doesn't compile in latest GHC HEAD, although it does if I remove the signature on foo'. Is this expected? Cheers, Ganesh {-# LANGUAGE TypeFamilies #-} module Test7 where type family Id a type instance Id Int = Int foo :: Id a -> Id a foo = id foo' :: Id a -> Id a foo' = foo