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[ghc.git] / testsuite / tests / typecheck / should_fail / T2714.hs
1 {-# LANGUAGE ScopedTypeVariables, RankNTypes #-}
2
3 -- #2714
4
5 module T2714 where
6
7 f :: ((a -> b) -> b) -> (forall c. c -> a)
8 f = ffmap
9
10 ffmap :: Functor f => (p->q) -> f p -> f q
11 ffmap = error "urk"
12
13 {-
14 a ~ f q
15 c ~ f p
16 (p->q) ~ (a->b) -> b
17
18 =>
19 a ~ f q
20 c ~ f p
21 p ~ a->b
22 q ~ b
23 =>
24 a ~ f b
25 c ~ f (a->b)
26 -}