[GHC] #11616: Kinds aren't instantiated

GHC ghc-devs at haskell.org
Wed May 3 13:04:22 UTC 2017


#11616: Kinds aren't instantiated
-------------------------------------+-------------------------------------
        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.1
      Resolution:                    |             Keywords:
                                     |  TypeApplications
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by RyanGlScott):

 Is this bug still present? I just tried defining this:

 {{{#!hs
 {-# LANGUAGE AllowAmbiguousTypes #-}
 {-# LANGUAGE TypeApplications #-}
 {-# LANGUAGE TypeInType #-}
 module T11616 where

 class Whoami a where
   whoami :: String

 instance Whoami Int where
   whoami = "int"

 instance Whoami Bool where
   whoami = "[y/n]"

 instance Whoami Maybe where
   whoami = "call me maybe"

 whoisint :: String
 whoisint = whoami @Int
 }}}

 And compiling it works without a hitch on GHC 8.0.1, 8.0.2, 8.2.1, and
 HEAD. So I suspect that the invisible kind variable is no longer available
 for type application, which is the behavior you desire, right goldfire?

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11616#comment:3>
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