[GHC] #11466: Constraint synonym with Implicit Parameter

20 Jan 2016


      #11466: Constraint synonym with Implicit Parameter
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           Reporter:  nomeata        |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.1
  (Type checker)                     |
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 This:
 {{{
 {-# LANGUAGE ConstraintKinds, ImplicitParams #-}
 module Foo where
 type Foo = ?foo::()
 }}}
 gives
 {{{
 Foo.hs:3:1: error:
     • Illegal implicit parameter ‘?foo::()’
     • In the type synonym declaration for ‘Foo’
 }}}
 in GHC HEAD. It used to work in GHC-7.10. Did not check GHC-8.0.

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Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11466
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