How much should we prioritize backward compatibility in this case? One possibility is to make `set?' mean `hash-set?', and add `generic-set?' in place of the current `set?'. That's uglier, obviously, but it would be better if we want to prioritize backward compatibility.
At Wed, 21 Aug 2013 19:14:06 -0400, Carl Eastlund wrote: > 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 > > > > > > > > > _________________________ > Racket Developers list: > http://lists.racket-lang.org/dev _________________________ Racket Developers list: http://lists.racket-lang.org/dev
