From Newsgroup: comp.lang.lisp

(loop for x in y
when (f x)
collect (g x))

Gauche Scheme:

(define f positive?)
(define (g x) (and (odd? x) (* x x)))
(define y (iota 22 -8))

(append-map
(lambda(x) (if (f x) (list (g x)) '()))
y)

===>
(1 #f 9 #f 25 #f 49 #f 81 #f 121 #f 169)
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