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* Is it possible to expand syntax inside match?
@ 2021-10-24  6:49 Михаил Бахтерев
  2021-10-24 19:48 ` Maxime Devos
  0 siblings, 1 reply; 2+ messages in thread
From: Михаил Бахтерев @ 2021-10-24  6:49 UTC (permalink / raw)
  To: guile-user

Greetings!

I wondering, if is it possible to implement something like
this?

(define-syntax R (syntax-rules () ((_ r v l) #(red r v l))))
(define-syntax B (syntax-rules () ((_ r v l) #(black r v l))))

(define red-black-set-balance 
  (match-lambda
    ((or (B (R (R a x b) y c) z d)
         (B (R a x (R b y c)) z d)
         (B a x (R (R b y c) z d))
         (B a x (R b y (R c z d)))) (R (B a x b) y (B c z d)))
    (node node)))

The idea is to have some automation allowing not to write
patterns manually:

  #('black #('red #('red a x b) y c) z d)

- Mikhail Bakhterev, respectfully.



^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: Is it possible to expand syntax inside match?
  2021-10-24  6:49 Is it possible to expand syntax inside match? Михаил Бахтерев
@ 2021-10-24 19:48 ` Maxime Devos
  0 siblings, 0 replies; 2+ messages in thread
From: Maxime Devos @ 2021-10-24 19:48 UTC (permalink / raw)
  To: Михаил
	Бахтерев,
	guile-user

Михаил Бахтерев schreef op zo 24-10-2021 om 11:49 [+0500]:
> Greetings!
> 
> I wondering, if is it possible to implement something like
> this?
> 
> (define-syntax R (syntax-rules () ((_ r v l) #(red r v l))))
> (define-syntax B (syntax-rules () ((_ r v l) #(black r v l))))
> 
> (define red-black-set-balance 
>   (match-lambda
>     ((or (B (R (R a x b) y c) z d)
>          (B (R a x (R b y c)) z d)
>          (B a x (R (R b y c) z d))
>          (B a x (R b y (R c z d)))) (R (B a x b) y (B c z d)))
>     (node node)))

Not exactly what you were looking for, but maybe use quasisyntax /
unsyntax #` #, something like (untested):

;; define, not define-syntax!
(define R (syntax-rules () ((_ r v l) #(red r v l))))
(define B (syntax-rules () ((_ r v l) #(black r v l))))

(define-syntax red-black-set-balance-m
  (lambda (s)
    #`(match-lambda
        ((or #,(B (R (R a x b) y c) z d)
             #,(B (R a x (R b y c)) z d)
             ...))
        (node node))))

(define red-black-set-balance red-black-set-balance-m)


Greetings,
Maxime




^ permalink raw reply	[flat|nested] 2+ messages in thread

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