Re: [plt-scheme] Defines in lets

[Eli Barzilay <eli@barzilay.org>]

On May 18, Max Hailperin wrote:
> There is nothing in standardized Scheme that neatly corresponds to
> what you are used to in Common Lisp.  Various Scheme implementations
> have non-standard extensions to the language that do what you want.
> If you want to stay within the standardized language, the closest
> you can come is:
> 
> (define set-x 'not-yet-set)  ; or any other placeholder value
> (define read-x 'not-yet-set)
> 
> (let ((x 0))
>   (set! set-x (lambda (y) (set! x y)))
>   (set! read-x (lambda () x)))

But if you're sticking with mzscheme, you can do this:

  (define-values (set-x read-x)
    (let ((x 0))
      (values (lambda (y) (set! x y))
              (lambda () x))))

-- 
          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                  http://www.barzilay.org/                 Maze is Life!