Re: [GHC] #12553: Reference kind in a type instance declaration defined in another instance declaration

15 Aug 2017

      #12553: Reference kind in a type instance declaration defined in another instance
declaration
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        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:  worksforme        |             Keywords:  TypeInType
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by goldfire):

 * status:  new => closed
 * resolution:   => worksforme

Comment:

 The program below, taken from the original ticket description, compiles on
 HEAD and 8.2.1:

 {{{#!hs
 {-# LANGUAGE PolyKinds, DataKinds, TypeFamilies #-}

 module Bug where

 import Data.Kind

 data Sig a = Full a | a :-> Sig a

 data AST :: (Sig a -> Type) -> (Sig a -> Type)

 -- ASTF :: (Sig a -> Type) -> (a -> Type)
 type ASTF dom a = AST dom (Full a)

 class Syntactic a where
   type Domain   a :: Sig u -> Type
   type Internal a :: u
   desugar :: a -> ASTF (Domain a) (Internal a)
   sugar   :: ASTF (Domain a) (Internal a) -> a
 }}}

 There's been a lot of other chatter on this ticket, but if there is still
 an issue here, please open a new ticket.

-- 
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12553#comment:10
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