[racket-dev] [plt] Push #27395: master branch updated

I was thinking of the `Set' type constructor as meaning generic set,
which is why I gave that type to `generic-set?'. This interpretation is
a problem because TR treats sets as covariant.

If we make sets invariant, could TR support generic sets? [1] Or are
there other issues I'm missing?

Vincent


[1] Better support would also include subtyping between lists and sets.


At Fri, 30 Aug 2013 16:38:11 -0700,
Eric Dobson wrote:
> 
> Isn't the assymetric check the wrong way? If it returns true, we know
> nothing because it might not be a hash-set, but if it returns false
> then we know that it is not a hash set?
> 
> On Fri, Aug 30, 2013 at 3:30 PM, Asumu Takikawa <asumu at ccs.neu.edu> wrote:
> > On 2013-08-30 16:15:23 -0400, Sam Tobin-Hochstadt wrote:
> >> I worry about mutable sets here, but I can't think of any bugs it can
> >> cause ATM.
> >
> > I don't have any segfault-causing bugs, but here's a violation of the blame
> > theorem:
> >
> >   #lang racket
> >
> >   (module a0 racket
> >     (define s (mutable-set 1 2 3))
> >     (provide s))
> >
> >   (module a typed/racket
> >     (require/typed (submod ".." a0) [s Any])
> >     (: x (Setof Any))
> >     (define x (assert s generic-set?))
> >     (provide x))
> >
> >   (require 'a)
> >   x
> >
> > Cheers,
> > Asumu
> > _________________________
> >   Racket Developers list:
> >   http://lists.racket-lang.org/dev