XPost: comp.lang.scheme

(loop for x in things
when (foo-p x) collect x into foos
when (bar-p x) collect x into bars
when (and (foo-p x) (bar-p x)) collect x into both
finally (return (values foos bars both)))

It's shorter in Gauche Scheme.

(define things '(0 3 -5 4 9 -7 6 8))

(let@ (() odds posi both)
(dolist (x things)
(when (odd? x) (push! odds x))
(when (positive? x) (push! posi x)
(when (odd? x) (push! both x))))
(values odds posi both))

(-7 9 -5 3)
(8 6 9 4 3)
(9 3)

Given:

(define-macro let@
(lambda (lets . exprs)
(let ((lets lets)
(let-pairs '()))
(if (list? lets)
(while (pair? lets)
(let ((x (pop! lets)))
(cond
((not (symbol? x))
(while (pair? lets)
(push! let-pairs (list (pop! lets) x))))
((null? lets) (push! let-pairs (list x 0)))
(#t (push! let-pairs (list x (pop! lets)))))))
(set! let-pairs `((,lets 0))))
`(let* ,(reverse let-pairs)
,@exprs))))

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XPost: comp.lang.scheme

On 2024-09-26, B. Pym <Nobody447095@here-nor-there.org> wrote:

(loop for x in things
when (foo-p x) collect x into foos
when (bar-p x) collect x into bars
when (and (foo-p x) (bar-p x)) collect x into both
finally (return (values foos bars both)))

It's shorter in Gauche Scheme.

It's five physical nonblank lines of code.

(define things '(0 3 -5 4 9 -7 6 8))

1: (let@ (() odds posi both)
2: (dolist (x things)
3: (when (odd? x) (push! odds x))
4: (when (positive? x) (push! posi x)
5: (when (odd? x) (push! both x))))
6: (values odds posi both))

(-7 9 -5 3)
(8 6 9 4 3)
(9 3)

Given:

7: (define-macro let@
8: (lambda (lets . exprs)
9: (let ((lets lets)
10: (let-pairs '()))
11: (if (list? lets)
12: (while (pair? lets)
13: (let ((x (pop! lets)))
14: (cond
15: ((not (symbol? x))
16: (while (pair? lets)
17: (push! let-pairs (list (pop! lets) x))))
18: ((null? lets) (push! let-pairs (list x 0)))
19: (#t (push! let-pairs (list x (pop! lets)))))))
20: (set! let-pairs `((,lets 0))))
21: `(let* ,(reverse let-pairs)
22: ,@exprs))))

How is twenty-two nonblank lines shorter than five?

You are clearly not well.

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