[GHC] #14042: Datatypes cannot use a type family in their return kind

[GHC]

#14042: Datatypes cannot use a type family in their return kind
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.0.1
  checker)                           |             Keywords:  TypeInType,
      Resolution:                    |  TypeFamilies
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by goldfire):

 This ticket is actually about regular old datatypes, not data families.
 Let's solve the datatype problem first, I think. The only part I haven't
 quite figured out is if we need the coercion relating the declared return
 kind to `Type` somewhere, but I don't see where it would go, other than
 the types of constructors. What would the constructor workers look like?
 I'm not sure.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14042#comment:13>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler