Subject: Re: publish
From: Vassily Litvinov (vass@cs.washington.edu)
Date: Thu Mar 29 2001 - 12:42:38 PST
> > declaration
> > forall F where W1: object O1 where W2 isa O2, O3 subtypes T4;
> > desugars into:
> > forall F where W1,W2: object O1;
> > forall F where W1,W2: extend object O1 isa O2;
> > forall F where W1,W2: extend object O1 isa O3;
> > forall F where W1,W2: extend object O1 subtypes T4;
>
> What is the "where W2" clause for? You added it, right?
It used to be at the very end of the declaration, as in
forall F where W1: object O1 isa O2, O3 subtypes T4 where W2;
I changed the syntax in this respect, by moving it before all isa's.
I think this way it's clearer that this where clause is not specific to
"subtypes T4".
As a side note, I was going to allow a "where" clause after each
supertype, e.g.
forall F where W1: object O1 isa O2 where W2, O3 where W3, subtypes T4 where W4;
so that each subtyping link had it's own "where". But then there is
ambiguity in parsing. So if you need a "where" clause for the subtyping
link, create a separate "extend" declaration.
As I mentioned, the following now does the right thing:
extend i_vector[`T] subtypes i_vector[`S>=T];
Vass
>
> -- Craig
>
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