Opened 10 years ago

Closed 10 years ago

Last modified 8 years ago

#818 closed bug (fixed)

Uncaught kind error leads to the 'impossible' happening

Reported by: sweirich@… Owned by:
Priority: normal Milestone:
Component: Compiler Version: 6.4
Keywords: Cc:
Operating System: MacOS X Architecture: Unknown/Multiple
Type of failure: Test Case:
Blocked By: Blocking:
Related Tickets: Differential Rev(s):
Wiki Page:

Description (last modified by simonpj)

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.
/ /_\\/ __  / /___| |
\____/\/ /_/\____/|_|      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,

Change History (3)

comment:1 Changed 10 years ago by simonpj

  • Description modified (diff)

comment:2 Changed 10 years ago by simonpj

  • Resolution set to fixed
  • Status changed from new to closed

I think this is already fixed in 6.4.1. Try upgrading


Kind error: `F c' is not applied to enough type arguments In the data type declaration for `Val'


comment:3 Changed 8 years ago by simonmar

  • Architecture changed from Unknown to Unknown/Multiple
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