I would like to ask GHCi for the type that a type expression will evaluate to, once all definitions of type synonyms and (when possible) type families have been inlined. It appears that I can do some part of this for type T by using ":t undefined :: T": type family F a type instance F Int = Bool type instance F Bool = Int type instance F (a, b) = (F a, F b) ghci> :t undefined :: F (Int, Bool) undefined :: F (Int, Bool) :: (Bool, Int) I also get what I expect here: ghci> :t undefined :: F (a, Bool) undefined :: F (a, Bool) :: (F a, Int) Of course, this doesn't work on types of kinds other than *. Is it possible and worth having another GHCi command to perform this operation for any types? It could be the type analogue to :t such that it evaluates the type and gives its kind. Regards, Sean