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 -> y
Tested 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 |