[GHC] #9123: Need for higher kinded roles

[GHC]

#9123: Need for higher kinded roles
-------------------------------------+------------------------------------
        Reporter:  simonpj           |            Owner:
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.8.2
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
-------------------------------------+------------------------------------

Comment (by simonpj):

 Edward, can you elaborate the "without it you cannot write.." issue,
 perhaps on the wiki page, so we have it recorded properly?

 In the short term (i.e. before we converge on a better design for roles) I
 think we have these alternatives:
  * Defer AMP altogether (very undesirable)
  * Remove `join` from `Monad` in the AMP story (better)
  * Adopt full AMP (`join` and all), but accept that GND `deriving( Monad
 )` won't work for some monad transformers; you have to write it by hand.

 I am agnostic. It's a library issue.   Edward, which would you like?

 Simon

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9123#comment:12>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler