testsuite/tests/typecheck/should_fail/tcfail188.hs

   1 {-# LANGUAGE RankNTypes, KindSignatures #-}
   2 {-# OPTIONS_GHC -Werror #-}
   3
   4 -- Trac #959
   5
   6 module ShouldFail where
   7
   8 data D (f :: (* -> *) -> * -> *) (af :: * -> *) (ax :: *) =
   9   D (af (f af ax))
  10
  11 data CList (f :: (* -> *) -> * -> *) (a :: *) =
  12   RCons a (CList (D f) a)
  13
  14 type CycleList a = forall f. CList f a
  15
  16 chead :: CycleList a -> a
  17 chead ys = case ys of (RCons x xs) -> x