Fix 'SPECIALISE instance'
[ghc.git] / testsuite / tests / indexed-types / should_compile / T12444a.hs
1 {-# LANGUAGE KindSignatures, TypeFamilies, GADTs, DataKinds #-}
2
3 module T12444a where
4
5 type family F a :: *
6 type instance F (Maybe x) = Maybe (F x)
7
8 foo :: a -> Maybe (F a)
9 foo = undefined
10
11 -- bad :: (F (Maybe t) ~ t) => Maybe t -> [Maybe t]
12 bad x = [x, foo x]