On Fri, Aug 30, 2013 at 8:40 PM, Eric Dobson <eric.n.dob...@gmail.com> wrote: > As it stands the Set type constructor is for hash sets. Changing that > would break backwards compatibility and pr13989 is for the issue of > changing the meaning/any change. > > I think there is a bunch of existing code that assumes that Set is > exactly hashsets, or at least covariant.
I think we, like Racket in general, should probably follow the slightly more awkward path that Carl ended up on for backwards compatibility, with `set?` for immutable hash sets, and `generic-set?` for generic sets, and similarly for the type names. Sam > > On Fri, Aug 30, 2013 at 5:37 PM, Vincent St-Amour <stamo...@ccs.neu.edu> > wrote: >> 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 <as...@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 _________________________ Racket Developers list: http://lists.racket-lang.org/dev
