[racket] macro question

From: Jay McCarthy (jay.mccarthy at gmail.com)
Date: Thu Sep 25 10:17:49 EDT 2014

I won't answer the question about R5RS, but in Racket you can do this
fairly succinctly:

#lang racket/base
(require (for-syntax racket/base

(define-syntax (vars stx)
  (syntax-case stx ()
    [(_ id count val)
         ([(id_i ...)
           (for/list ([i (in-range 1 (add1 (syntax->datum #'count)))])
             (format-id #'id "~a~a" #'id i))])
     (syntax/loc stx
       (begin (define id_i val)

(vars id 5 null)

(vector id1 id2 id3 id4 id5)

2014-09-24 22:35 GMT-04:00 Alejandro Zamora <terefv at ltu.sld.cu>:
> Hi Racket people:
>         I have a (maybe too simple) question:
>         How I create one macro like this (but using define-macro &
>         R5RS language only)?:
>         (vars sym var-cant val-of-vars)
>         Example:
>         (vars id 5 null) -> (prog (define id1 null)
>                                   (define id2 null)
>                                   (define id3 null)
>                                   (define id4 null)
>                                   (define id5 null))
> --
> Nunca digas nunca, di mejor: gracias, permiso, disculpe.
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Jay McCarthy

           "Wherefore, be not weary in well-doing,
      for ye are laying the foundation of a great work.
And out of small things proceedeth that which is great."
                          - D&C 64:33

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