inferred type doesn't type-check (using type families)

Hi, Compiling

class WithT a where type T a

f :: T a -> a -> T a f = undefined

g x = f x 42

with -XTypeFamilies -fwarn-missing-signatures gives: Inferred type: g :: forall a. (Num a) => T a -> T a Adding

g :: Num a => T a -> T a

results in: Couldn't match expected type `T a' against inferred type `T a1' In the first argument of `f', namely `x' Is the inferred type not the right one? Is g typeable? Best, Roland -- http://alacave.net/~roland/