[plt-scheme] How to make a setter out of an identifier

From: Cheng-Chang Wu (chengchangwu at yahoo.com)
Date: Tue Nov 3 20:19:15 EST 2009


I am new to the brave scheme world, and trying hard to understand the secrets of macro.

I want to do the following: take an identifier and make a setter out of the identifier.

For example,

(define kk 0)
(make-setter kk)

should give me a set-kk! which can be used to set the value of kk.

The best macro I can image is 

(define-syntax make-setter
  (lambda (x)
    (syntax-case x ()
        ((make-setter id)
                 (syntax k)
                 `(define (,(string->symbol (string-append "set-" (symbol->string 'id) "!")) a-value) (set! id a-value)))))
           (syntax def))))))

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