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Re: Is it possible to expand syntax inside match?
From: |
Maxime Devos |
Subject: |
Re: Is it possible to expand syntax inside match? |
Date: |
Sun, 24 Oct 2021 19:48:01 +0000 |
User-agent: |
Evolution 3.38.3-1 |
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