Forum: Too Lazy BBS

Re: Speed up interpolation

From B. Pym@Nobody447095@here-nor-there.org to comp.lang.lisp on Tue Aug 12 15:57:09 2025

From Newsgroup: comp.lang.lisp

Rainer Joswig wrote:

(loop with result = initial-result-value
for a in list ; map over the list
when (keep-p a) ; filter out
do (setf result (reduction-op (op a) result)
finally (return result))

for example

(loop with result = ()

Wrong.

() is not a number.

for a in list
when (evenp a)
do (setf result (* (sqrt a) result))
finally (return result))

(let ((seq '(2 3 4 5 6)))
(do ((result 1 (if (evenp x) (* x result) result))
x)
((null seq) result)
(setf x (pop seq))))

===>
48
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