Existential quantification

Johan Nordlander nordland@cse.ogi.edu
Thu, 22 Feb 2001 14:53:14 -0800

George Russell wrote:
> Excuse me, but is it a bug or a feature that Hugs (98-Feb2001), with
> the -98 option, rejects:
> data G b = forall a . H a b =>  G a b
> class H a b where
> with "Variable "b" in constraint is not locally bound"?

As far as I can understand the restriction is there on purpose, although that
purpose might just be to avoid trouble with the particular implementation of
local existential quantification that comes with Hugs.  In principle there
shouldn't be any problem removing this restriction, however, I'll have to look
at the code more carefully before I can make any promise about doing so in a
future release.

-- Johan