type unsafety with type family + GADT
Here's unsafeCoerce:
type family Const a
type instance Const a = ()
data T a where T :: a -> T (Const a)
coerce :: forall a b . a -> b
coerce x = case T x :: T (Const b) of
T y -> yTested with GHC 6.9.20070918
Maybe, see also #345
Trac metadata
| Trac field | Value |
|---|---|
| Version | 6.8 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler (Type checker) |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | Unknown |
| Architecture | Unknown |