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comp.lang.lisp

Re: simple loop question

William James

9/15/2015 11:21:00 PM

Lars Brinkhoff wrote:

> > use LOOP to collect random integers into a list until the sum of that
> > list exceeds a constant (say 50).
>
> (loop for x = (random 10) collect x sum x into y until (> y 50))

Instead of a macro whose source measures more than
60 kilobytes, we can simply use recursion.

Of course, we can't do that in CL (COBOL-Like), because
any time you use recursion in CL you risk stack-overflow.
Yes, CL is such an ancient, clunky, un-Lispy language
that it doesn't even have TCO.

Gauche Scheme:

(use srfi-27 :only (random-integer))

(let g ((lst ()) (sum 0))
(if (> sum 50)
lst
(let1 x (random-integer 10)
(g (cons x lst) (+ x sum)))))

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