> Then suppose you later need the loop/map to collect some of the values
> under certain conditions. You might have
>
> (loop for x in (get-list)
> for i from 0
> do (format t "~A - ~A~%" i x)
> if (test x)
> collect (foo x))

Gauche Scheme

(use srfi-13) ;; string-upcase

(filter-map
(lambda (x i) (print i " - " x)
(and (string? x) (string-upcase x)))
'(foo "an" 8 "why")
(lrange 0))

0 - foo
1 - an
2 - 8
3 - why
("AN" "WHY")

B. Pym wrote:

> > Then suppose you later need the loop/map to collect some of the values
> > under certain conditions. You might have
> >
> > (loop for x in (get-list)
> > for i from 0
> > do (format t "~A - ~A~%" i x)
> > if (test x)
> > collect (foo x))
>
> Gauche Scheme
>
> (use srfi-13) ;; string-upcase
>
> (filter-map
> (lambda (x i) (print i " - " x)
> (and (string? x) (string-upcase x)))
> '(foo "an" 8 "why")
> (lrange 0))
>
> 0 - foo
> 1 - an
> 2 - 8
> 3 - why
> ("AN" "WHY")

> Suppose you have
>
> (loop for x in (get-list)
> do (format t "~A~%" x))
>
> and then it turns out you need to print a numeric index. You can do
>
> (loop for x in (get-list)
> for i from 0
> do (format t "~A - ~A~%" i x))
>
> If you start with
>
> (mapc (lambda (x) (format t "~A~%" x)) (get-list))
>
> it seems (to me) that it'd be harder to modify it as needed,
>
> (let ((list (get-list)))
> (mapc (lambda (i x) (format t "~A - ~A" i x))
> (range 0 (length list))
> list))
>
> (I'm assuming the toolkit includes a RANGE utility, or something similar.)

Gauche Scheme

Shorter than the loop:

(for-each
(pa$ format #t "~a - ~a\n")
(lrange 0)
'(a b c))

0 - a
1 - b
2 - c