> > > KMP: The example you cite is quite simplistic.....snip...A
> > > loop like this:
> > >
> > > (loop for x from 0
> > > for y in some-list
> > > when (good-result? y)
> > > collect (list x y))
> > >
> > > is easy to write and maintain, and much easier to explain than the
> > > equivalent, but more Lispy:
> > >
> > > (do ((x 0 (+ x 1))
> > > (y-list some-list (cdr y-list))
> > > (result '()))
> > > ((null y-list) ;; [fixed]
> > > (nreverse result))
> > > (let ((y (first y-list)))
> > > (when (good-result? y)
> > > (push (list x y) result))))

Gauche Scheme:

(filter-map
(lambda (x i) (and (odd? x) (list i x)))
'(3 4 5 7 8)
(liota))

===>
((0 3) (2 5) (3 7))