[GHC] #11411: GHC allows you to quantify variables over TYPE 'Unlifted (a.k.a, #)

11 Jan 2016


      #11411: GHC allows you to quantify variables over TYPE 'Unlifted (a.k.a, #)
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           Reporter:  RyanGlScott    |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.1
  (Type checker)                     |
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  GHC accepts
  Unknown/Multiple                   |  invalid program
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 This should be disallowed, so [https://phabricator.haskell.org/D1757
 sayeth goldfire]:

 {{{
 $ inplace/bin/ghc-stage2 --interactive
 GHCi, version 8.1.20160109: http://www.haskell.org/ghc/  :? for help
 λ> :set -XKindSignatures
 λ> import GHC.Types
 λ> data Wat (a :: TYPE 'Unlifted) = Wat a
 λ> :i Wat
 data Wat (a :: #) = Wat a       -- Defined at <interactive>:3:1
 λ> :set -XMagicHash
 λ> :t Wat 1#
 Wat 1# :: Wat GHC.Prim.Int#
 λ> :t Wat 'a'#
 Wat 'a'# :: Wat GHC.Prim.Char#
 }}}

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Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11411
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