[Haskell-cafe] Can someone explain this typing restriction?

[Gerrit van den Geest]

Gerrit van den Geest wrote:
>
>> I had a feeling this was discussed in "Typing Haskell in Haskell" by 
>> Mark Jones, but after a quick skim I can't find it again (I thought 
>> it would be
>> in Section 11.6 of his paper).   
>
> It is, on page 35 (section 11.6.3) of "Typing Haskell in Haskell" by 
> Mark Jones.
Quote:

"This is a consequence of a throw-away comment specifying that all 
explicit type signatures in a binding group must have the same context 
up to renaming of variables. This is a syntactic restriction that can 
easily be checked prior to type checking. Our comment here, however, 
suggest that it is unnecessarily restrictive."


I agree with Mark Jones, the Haskell compiler Helium for example doesn't 
have this restriction.

I think this issue is also related to the following Haskell' ticket:
http://hackage.haskell.org/trac/haskell-prime/ticket/65


Gerrit