Re: the "loop" macro

B. Pym wrote:

B. Pym wrote:
 

B. Pym wrote:
 

 (loop for item in list
       maximize (f item))

 
It's shorter in Gauche Scheme.
 
(use srfi-42)   ;; max-ec
 
(max-ec (: x '(-8 2 0)) (abs x))
  ===>
8

 

 (loop for x in '(1 2 3 4 5 6 7)
    when (evenp x)
     collect x into evens
    else
     collect x into odds
    finally
     (return (values evens odds)))
 => (2 4 6), (1 3 5 7)

 
It's shorter in Gauche Scheme.
 
(partition even? '(2 3 4 5 6 7))
  ===>
(2 4 6)
(3 5 7)

Using collectors.

(let ((odds (mlistbag)) (evens (mlistbag)))
  (dolist (x '(1 2 3 4 5 6 7))
    (if (odd? x) (odds x) (evens x)))
  (values (evens) (odds)))

  ===>
(2 4 6)
(1 3 5 7)


Given:

(define (mbag init func :optional (pass-through #f))
  (let ((val init) (func func) (pass-through pass-through))
    (lambda args
      (if (null? args)
        val
        (begin
          (set! val
            ;; A "kons" may have been supplied.
            ((if (null? (cdr args)) func (cadr args))
              (car args) val))
          (if pass-through
            (car args)
            val))))))
(define (mlistbag :optional (pass-through #t))
  (let ((bag (mbag '() cons pass-through)))
    (lambda args
      (if (null? args)
        (reverse (bag))
        (apply bag args)))))