Re: expression and definition context in Scheme

[Damien Mattei]

On Wed, Aug 31, 2022 at 5:29 PM Maxime Devos <maximedevos@telenet.be> wrote:

>
> On 31-08-2022 09:01, Damien Mattei wrote:
> > I always try to keep compatibility with RnRS and in fact except cond
> > none of when, unless, cond, case, while, and do are in standart RnRS
> schem
>
> 'when', 'unless' and 'do' are actually RnRS, see (rnrs control).
>

oh your're right...i was sticked to R5RS ,time i was student...

>
> 'case' is also RnRS, see (rnrs base).
>
> However, looking at (guile)while do, 'while' is indeed non-standard.
>

and i had rewritten last week a 'while ... do' like in C or Pascal:
https://www.tutorialspoint.com/pascal/pascal_while_do_loop.htm
https://www.tutorialspoint.com/cprogramming/c_while_loop.htm

in my Scheme+:

;; (define do '())
;; (while {i < 4}
;;    do
;;      (display i)
;;      (newline)
;;      {i <- {i + 1}})
;; 0
;; 1
;; 2
;; 3
;; $1 = #f
(define-syntax while
  (syntax-rules (while do)
    ((_ pred do b1 ...)
     (let loop () (when pred b1 ... (loop))))))

i will have to forget it! as i want to keep compatibility with standard
Scheme also but i will rewrite all with (let () ...) instead of (begin ...)
unless it can cause some incompatibilities, for now , i do not see problems
as "who can do more can do less"......

Regards,
Damien

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