:kind! doesn't reduce type families with poly-kinded return kinds
Originally discovered here, here is a simplified example:
$ ghci
GHCi, version 7.10.3: http://www.haskell.org/ghc/ :? for help
λ> :set -XPolyKinds -XTypeFamilies
λ> type family Hm :: k where Hm = Int
λ> :kind! Hm
Hm :: k
= HmGiving Hm a monomorphic return kind of * makes it work with :kind!:
$ ghci
GHCi, version 7.10.3: http://www.haskell.org/ghc/ :? for help
λ> :set -XTypeFamilies
λ> type family Hm :: * where Hm = Int
λ> :kind! Hm
Hm :: *
= IntTrac metadata
| Trac field | Value |
|---|---|
| Version | 7.10.3 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | GHCi |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |