[racket-dev] [plt] Push #26936: master branch updated

Also if you're going to memoize things, why are you using assoc rather than
a hash table?  Or if at all possible, a weak hash table?

Carl Eastlund


On Thu, Jun 6, 2013 at 6:35 PM, Robby Findler
<robby at eecs.northwestern.edu>wrote:

> Can't we do better than a memo table?
>
>
> On Thursday, June 6, 2013, wrote:
>
>> stamourv has updated `master' from 5ea3a1ce6d to 6e8c9ed15a.
>>   http://git.racket-lang.org/plt/5ea3a1ce6d..6e8c9ed15a
>>
>> =====[ 2 Commits ]======================================================
>> Directory summary:
>>   82.9% collects/racket/contract/private/
>>   17.0% collects/scribblings/reference/
>>
>> ~~~~~~~~~~
>>
>> d1df869 Vincent St-Amour <stamourv at racket-lang.org> 2013-06-06 18:02
>> :
>> | Document procedure-closure-contents-eq?.
>> :
>>   M collects/scribblings/reference/procedures.scrbl | 5 +++++
>>
>> ~~~~~~~~~~
>>
>> 6e8c9ed Vincent St-Amour <stamourv at racket-lang.org> 2013-06-06 18:31
>> :
>> | Memoize wrapped case-> range contracts.
>> |
>> | Fixes failing contract tests.
>> :
>>   M collects/racket/contract/private/arrow.rkt | 21 +++++++++++++++------
>>
>> =====[ Overall Diff ]===================================================
>>
>> collects/racket/contract/private/arrow.rkt
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> --- OLD/collects/racket/contract/private/arrow.rkt
>> +++ NEW/collects/racket/contract/private/arrow.rkt
>> @@ -1712,12 +1712,21 @@ v4 todo:
>>                                            "the domain of"
>>                                            #:swap? #t)))
>>                                   dom-ctcs+case-nums)
>> -                            (map (λ (f)
>> -                                   (define p (f rng-blame))
>> -                                   (lambda args
>> -                                     (with-continuation-mark
>> -                                      contract-continuation-mark-key
>> blame
>> -                                      (apply p args))))
>> +                            (map (let ([memo '()])
>> +                                   ;; to preserve
>> procedure-closure-contents-eq?ness of the
>> +                                   ;; wrapped procedures, memoize with f
>> as the key.
>> +                                   (λ (f)
>> +                                     (define target
>> +                                       (assoc f memo
>> procedure-closure-contents-eq?))
>> +                                     (if target
>> +                                         (cdr target)
>> +                                         (let* ([p   (f rng-blame)]
>> +                                                [new (lambda args
>> +
>> (with-continuation-mark
>> +
>>  contract-continuation-mark-key blame
>> +                                                        (apply p
>> args)))])
>> +                                           (set! memo (cons (cons f new)
>> memo))
>> +                                           new))))
>>                                   rng-ctcs)))
>>        (define (chk val mtd?)
>>          (cond
>>
>> collects/scribblings/reference/procedures.scrbl
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> --- OLD/collects/scribblings/reference/procedures.scrbl
>> +++ NEW/collects/scribblings/reference/procedures.scrbl
>> @@ -88,6 +88,11 @@ to the wrong number of arguments, the resulting error
>> hides the first
>>  argument as if the procedure had been compiled with the
>>  @indexed-racket['method-arity-error] syntax property.}
>>
>> + at defproc[(procedure-closure-contents-eq? [proc1 procedure?]
>> +                                         [proc2 procedure?]) boolean?]{
>> +Compares the contents of the closures of @racket[proc1] and
>> @racket[proc2]
>> +for equality by comparing closure elements pointwise using @racket[eq?]}
>> +
>>  @; ----------------------------------------
>>  @section{Keywords and Arity}
>>
>>
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