Robert Strandh  <strandh@labri.u-bordeaux.fr> wrote:
+---------------
| The construction:
| 
|   (let ((x 0))
|     (defun f ()
|       ...))
| 
| in CL defines a global function with x in its environment.  The way to
| do that in Scheme (I claim) is:
| 
|   (define foo)
|   (let ((x 0))
|     (set! foo (lambda () ...)))
+---------------

Actually, the standard idiom for this in Scheme is simply:

    (define foo
      (let ((x 0))
        (lambda () ...)))

You only need "set!"s if you're going to create multiple closures
over shared variables:

    (define foo #f)
    (define bar #f)
    (define baz #f)
    (let ((x 0))
      (set! foo (lambda () ...))
      (set! bar (lambda () ...))
      (set! baz (lambda () ...)))

But that's admittedly ugly, which is why some Schemes provide a
multiple-value top-level define, e.g., MzScheme:

    (define-values (foo bar baz)
      (let ((x 0))
	(values
          (lambda () ...)
          (lambda () ...)
          (lambda () ...))))

In Common Lisp, of course, the original example extends trivially:

    (let ((x 0))
      (defun foo () ...)
      (defun bar () ...)
      (defun baz () ...))


-Rob

-----
Rob Warnock, 30-3-510		<rpw3@sgi.com>
SGI Network Engineering		<http://www.meer.net/~rpw3/>
1600 Amphitheatre Pkwy.		Phone: 650-933-1673
Mountain View, CA  94043	PP-ASEL-IA

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