Ah, yes. The set? predicate no longer distinguishes a representation. There are several predicates for the original set type, now called "hash sets": set-eq?, set-eqv?, set-equal?, set-mutable?, set-immtuable?, and set-weak?. I didn't add the basic "hash-set?", but perhaps I should. It's a weird name, since "hash-set" and "hash-set!" are already existing, unrelated functions.
Carl Eastlund On Wed, Aug 21, 2013 at 7:08 PM, J. Ian Johnson <i...@ccs.neu.edu> wrote: > Okay, I can abide. However, that doesn't really get at my frustration. I'm > using the set constructor, that appears to now be an immutable-custom-set > with make-immutable-hash as its make-table. So what I'm looking for is not > set?, but set-immutable?, as it's a distinct (family of) struct types that > won't clash with the primitive data that I'm otherwise using. > -Ian > ----- Original Message ----- > From: "Carl Eastlund" <c...@ccs.neu.edu> > To: "J. Ian Johnson" <i...@ccs.neu.edu> > Cc: "dev" <dev@racket-lang.org> > Sent: Wednesday, August 21, 2013 6:58:56 PM GMT -05:00 US/Canada Eastern > Subject: Re: [racket-dev] Lists aren't sets, but have set-like operations > > > Ian, sets are now a generic datatype, like dictionaries. Association lists > are dictionaries, and lists are now sets. They're also streams and > sequences. They're not just "set-like". > > > > Carl Eastlund > > > On Wed, Aug 21, 2013 at 6:56 PM, J. Ian Johnson < i...@ccs.neu.edu > > wrote: > > > I just wasted about 2 hours tracking down a bug that ended up being due to > (set? '()) now evaluating to #t. I have no problems with set-union, > intersection, etc. being defined for lists, but to treat lists as sets > always is perverse to me. The contracts for set operations should use > set-like? for (or/c set? list?) and keep the two constructions separate. > > This conflation is almost as bad as treating empty list as false. > > -Ian > _________________________ > Racket Developers list: > http://lists.racket-lang.org/dev > > > >
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