This is probably not a very good idea for numerous reasons, but here's
one way to do that:
(just extend the 'define' to set! things that are already bound)
#lang racket
(require
(rename-in racket/base [define define-original])
(for-syntax syntax/parse))
(define-syntax (define stx)
(syntax-parse stx
[(define i:id v:expr) (if (identifier-binding #'i)
#'(set! i v)
#'(define-original i v))]
[(define (f:id arg:id ...) body ...)
(if (identifier-binding #'f)
#'(set! f (lambda (arg ...) body ...))
#'(define-original (f arg ...) body ...))]))
(define (func x) 3)
(define (func a b) b)
(define x 4)
(define x 2)
Cheers!
-- caner
On 10/26/2016 07:41 AM, İlker Kesen wrote:
Hi,
I want to allow redefinition of already defined expressions (variables,
procedures etc.), but Racket prevents me. I know, in DrRacket I can allow it
via graphical preferences interface for Pretty Big and R5RS languages. However,
I want to allow that operation in racket and sicp languages, too. There's no
option for those languages in that graphical interface and no documentation,
too (at least I couldn't have found). My question is, how can I do that? I want
to allow multiple re-definitions over and over again, not just for once. Here,
I attach an example and it's output.
Thanks in advance.
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