15 Sep
2011
15 Sep
'11
00:46
Take a look at: http://en.wikipedia.org/wiki/Closure_%28computer_science%29
On a final note, I am mystified as to how the code works. This is an example of it being defined and run on my Windows 7x64 machine:
Gambit v4.6.1
(define (counter)
(let ((value 0)) (lambda () (set! value (+ value 1)) value)))(define first-counter (counter)) (first-counter)
1
(first-counter)
2
(first-counter)
3
(first-counter)
4
It seems to initialize value to 0 and I assume that happens the first time you use (counter) to define another form. What I don't understand is why the code for initializing is skipped every time (first-counter) is run.
TIA, Steve
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