panic:Unify.unifyTauTyLists

The attached sample program triggers a panic because I forgot to 
pass the type argument in the recursive algebraic datatype 
construction. The commented line is correct.
GHC should not panic but instead provide a helpful error message.
(Unluckily, I won't be able to test this with -HEAD atm)

Compiling Main             ( bugs.hs, interpreted )
ghc-6.4: panic! (the `impossible' happened, GHC version 6.4):
        Unify.unifyTauTyLists: mismatched type lists!

Trac metadata

Trac field	Value
Version	6.4
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	ResolvedDuplicate
Component	Compiler (Type checker)
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