[GHC] #818: Uncaught kind error leads to the 'impossible' happening

[GHC]

#818: Uncaught kind error leads to the 'impossible' happening
-------------------------------------+--------------------------------------
  Reporter:  sweirich at cis.upenn.edu  |          Owner:         
      Type:  bug                     |         Status:  new    
  Priority:  normal                  |      Milestone:         
 Component:  Compiler                |        Version:  6.4    
  Severity:  normal                  |     Resolution:         
  Keywords:                          |             Os:  MacOS X
Difficulty:  Unknown                 |   Architecture:  Unknown
-------------------------------------+--------------------------------------
Old description:

> data F c a = F (c a)
>
> data Val c a = Val (F c) a  --- should produce a kind error but doesn't
>
> t = Val (F [True]) False --- here we get the impossible
>
> ---------------------------------------
> dhcp38-137:~/writing/exrep sweirich$ ghci test.hs
>    ___         ___ _
>   / _ \ /\  /\/ __(_)
>  / /_\// /_/ / /  | |      GHC Interactive, version 6.4, for Haskell 98.
> / /_\\/ __  / /___| |      http://www.haskell.org/ghc/
> \____/\/ /_/\____/|_|      Type :? for help.
>
> Loading package base-1.0 ... linking ... done.
> Compiling Main             ( test.hs, interpreted )
> ghc-6.4: panic! (the `impossible' happened, GHC version 6.4):
>         Unify.unifyTauTyLists: mismatched type lists!
>
> Please report it as a compiler bug to glasgow-haskell-bugs at haskell.org,
> or http://sourceforge.net/projects/ghc/.

New description:

 {{{
 data F c a = F (c a)

 data Val c a = Val (F c) a  --- should produce a kind error but doesn't

 t = Val (F [True]) False --- here we get the impossible
 }}}
 Here is a run
 {{{
 dhcp38-137:~/writing/exrep sweirich$ ghci test.hs
    ___         ___ _
   / _ \ /\  /\/ __(_)
  / /_\// /_/ / /  | |      GHC Interactive, version 6.4, for Haskell 98.
 / /_\\/ __  / /___| |      http://www.haskell.org/ghc/
 \____/\/ /_/\____/|_|      Type :? for help.

 Loading package base-1.0 ... linking ... done.
 Compiling Main             ( test.hs, interpreted )
 ghc-6.4: panic! (the `impossible' happened, GHC version 6.4):
         Unify.unifyTauTyLists: mismatched type lists!

 Please report it as a compiler bug to glasgow-haskell-bugs at haskell.org,
 or http://sourceforge.net/projects/ghc/.
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/818>
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