blob: 2222442bb38377c4da84174392d79060719c29bc (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
|
{-# LANGUAGE Haskell2010 #-}
{-# LANGUAGE RoleAnnotations, FlexibleContexts #-}
unit p where
signature A where
type role T nominal
data T a = T
module B where
import Data.Coerce
import A
f :: Coercible (T a) (T b) => a -> b
f x = x
unit a where
module A where
data T a = T
unit q where
dependency p[A=a:A]
module C where
import B
g :: a -> b
g = f
-- Either:
-- a) B should fail to typecheck against the signature, or
-- b) A should fail to match against the signature
|
