This means I can't interchange between mutable and immutable sets for my functions that only need to read generic sets, unless we further subdivide and have gen:set-query gen:set-constructor gen:set-mconstruct.
-Ian ----- Original Message ----- From: "Jay McCarthy" <jay.mccar...@gmail.com> To: "Carl Eastlund" <c...@ccs.neu.edu> Cc: "Racket Developers" <dev@racket-lang.org> Sent: Wednesday, October 2, 2013 3:23:07 PM GMT -05:00 US/Canada Eastern Subject: Re: [racket-dev] Generics updates Regarding a point from RacketCon, I don't like that gen:set includes functions like set-add! and set-remove!. I think that sets with mutations are subclass of get:set and we should have a separate gen:mset (or something) interface for mutable versions. I dislike that an obvious implementation of sets, hash tables, are not sets to gen:set, because there are operations that cannot be performed on them. I think that "X implements generic G" should imply "All functions of G work on X". But this is not the case with gen:set and hasheq sets, for instance. Jay On Tue, Jul 23, 2013 at 9:37 AM, Carl Eastlund <c...@ccs.neu.edu> wrote: > My work on adding gen:set, and related changes to define-generics and > gen:dict, is ready for review and (hopefully) to push to the master branch. > The branch moved in the process of cleaning things up, it's now at: > > https://github.com/carl-eastlund/racket/tree/generics-from-scratch > > (The "from scratch" just refers to the process of rebuilding the git > history, I didn't go out of my way to rewrite anything in the code base from > scratch, although in some places a lot of code did move around.) > > What's new in the branch: > > - Generics now support a few new options > - #:fallbacks specifies fallback method implementations for instances with > no implementation > - #:fast-defaults specifies instances on a "fast path", useful for > built-in types > - #:defined-predicate gives a more intuitive and efficient interface than > #:defined-table > - #:derive-property allows generics to piggy-back on existing struct > properties > > - Sets are now a generic datatype through gen:set > - lists are now sets > - the built-in set types are now documented as "hash sets" > - there are mutable and weak hash sets > - you can define new set types quickly with define-custom-set-types > - most set operations are now methods with fallbacks > - sets now support -copy and -clear operations, plus mutating [!] versions > of operations > > - Dictionaries have a few changes > - new macro define-custom-hash-types [*] > - most dict operations are now methods with fallbacks > - dicts now support -copy, -clear, -clear!, and -empty? operations > > I've run some benchmarks and performance of the various generic operations > are comparable to the current HEAD, so there should be no major performance > changes with this patch. > > [*] I've added define-custom-hash-types and define-custom-set-types rather > than just adding make-custom-set akin to make-custom-hash because > make-custom-hash is hard to use. The documented behavior -- that any custom > hash is equal to any other created with the same bindings and predicates / > hash functions -- was never true and can be expensive or at least tricky to > implement. It seemed more sensible to just remove the erroneous > documentation on make-custom-hash, and add the definition form to create > constructors for new, explicitly-compatible dict and set types. Both > definition forms bind predicates and constructors for new (set or dict) > types with immutable, mutable, and weak variants that inter-operate. > > If there are no serious issues brought up in the next day or two, I'll push > it to the development branch, since our current release process isn't > following HEAD. > > Carl Eastlund > > _________________________ > Racket Developers list: > http://lists.racket-lang.org/dev > -- Jay McCarthy <j...@cs.byu.edu> Assistant Professor / Brigham Young University http://faculty.cs.byu.edu/~jay "The glory of God is Intelligence" - D&C 93 _________________________ Racket Developers list: http://lists.racket-lang.org/dev _________________________ Racket Developers list: http://lists.racket-lang.org/dev