* is not an indexed type family
I can't seem to create an indexed data family using the kind * with -XTypeInType enabled. I have to work around it by using Type:
$ /opt/ghc/head/bin/ghci
GHCi, version 8.1.20160108: http://www.haskell.org/ghc/ :? for help
λ> :set -XTypeInType -XTypeFamilies
λ> import Data.Kind
λ> data family IdxProxy k (a :: k)
λ> data instance IdxProxy * a
<interactive>:5:1: error:
• Illegal family instance for ‘*’
(* is not an indexed type family)
• In the data instance declaration for ‘*’
λ> data instance IdxProxy Type a
λ> :kind! IdxProxy *
IdxProxy * :: * -> *
= IdxProxy *
λ> :kind! IdxProxy Type
IdxProxy Type :: Type -> *
= IdxProxy TypeTrac metadata
| Trac field | Value |
|---|---|
| Version | 8.1 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler (Type checker) |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | goldfire |
| Operating system | |
| Architecture |