[ ghc-Bugs-454716 ] 0 parameter type classes

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Bugs item #454716, was opened at 2001-08-23 14:23
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Category: Compiler (Type checker)
Group: 5.00
>Status: Closed
>Resolution: Fixed
Priority: 5
Submitted By: Iavor S. Diatchki (iavor_sd)
Assigned to: Nobody/Anonymous (nobody)
Summary: 0 parameter type classes

Initial Comment:
This seems to be a problem:

Program:

class Tag where
    f :: Char

main = main 


Output:
 
ghc -c -fglasgow-exts bug_ghc.hs

bug_ghc.hs:2:
    The constraint `Tag' does not mention any of the 
universally quantified type variables
        in the type `(Tag) => Char'
    In the class declaration for `Tag'



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>Comment By: Simon Peyton Jones (simonpj)
Date: 2001-08-24 01:00

Message:
Logged In: YES 
user_id=50165

Good point.

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