Hi Alexander, Thanks for your reply: I had something similar in mind (maybe I should check out math/array). I was just wondering if there was something more Racket-like (it still feels that SRFI is somewhat 'foreign' hack). And my last question remains: wouldn't it be beneficial to have such a generalised 'set!' system-wide? I understand that Racket focusses more on immutable structures, but there are still vectors and hash-tables which are inherently mutable and still have their niche.
Best regards, Alexey On 29 June 2015 at 18:36, Alexander D. Knauth <alexan...@knauth.org> wrote: > > On Jun 29, 2015, at 5:56 AM, Alexey Cherkaev <alexey.cherk...@gmail.com> > wrote: > > > For example, I was thinking of defining syntax to access my > implementation of multidimensional arrays > > as > > > > (define-syntax aref > > (syntax-rules (set!) > > [(set! (aref ?a ?i ...) ?v) (array-set! ?a ?i ... ?v)] > > [(aref ?a ?i ...) (array-ref ?a ?i ...)])) > > > > but obviously it won't work now as `set!` expects the `id` not an > expression (`syntax-id-rules` won't work either as `aref` is not an `id`). > > > #lang racket > (require srfi/17 math/array) > (define (aref a . is) > (array-ref a (list->vector is))) > (set! (setter aref) > (λ (a . is+v) > (match-define (list is ... v) is+v) > (array-set! a (list->vector is) v))) > (define a (mutable-array #[#[1 2] #[3 4]])) > (aref a 0 1) > (set! (aref a 0 1) 20) > (aref a 0 1) > > If you wanted, you could also define your own version of set! that does > what you want, which (I think) you would need to do if you needed aref to > be a macro. > > > -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
