I really like the new set features, especially mutable sets and lists as
sets.
Two things i have notices:
* The docs for set-intersect seem a bit mixed up with set-union stuff
* I could not get set-intersect on lists working, what i've tried
-> (set-intersect '(1 2 3) '(2 3 4))
; set-add: contract violation
; expected: set?
; given: 2
-> (set-intersect (list->set '(1 2 3)) '(2 3 4))
; set-intersect: set arguments have incompatible equivalence predicates
; first set: (set 1 2 3)
; incompatible set: '(2 3 4)
Tobias
On Tue, 23 Jul 2013 17:37:15 +0200, 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
--
---------------------------------------------------------
Tobias Hammer
DLR / Robotics and Mechatronics Center (RMC)
Muenchner Str. 20, D-82234 Wessling
Tel.: 08153/28-1487
Mail: tobias.ham...@dlr.de
_________________________
Racket Developers list:
http://lists.racket-lang.org/dev
