Closed type families break substitution
This code causes a Core Lint error:
{-# LANGUAGE TypeFamilies #-}
type family F a b where
F (Maybe a) [a] = Int
F b c = Bool
data Proxy a = P
type family G
foo :: Proxy d -> F d d -> Bool
foo _ = not
bar :: Bool -> Bool
bar = foo (P :: Proxy G)The solution needs to freshen variables before doing apartness checking. I will fix in due course.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 7.7 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |