Pascal Costanza wrote:

> What about dealing with an arbitrary number of filters?
>
> (defmacro predicate-collect (list &body predicates)
> (let ((collectors (mapcar (lambda (predicate)
> (declare (ignore predicate))
> (gensym "COLLECT"))
> predicates))
> (collect-t (gensym "COLLECT")))
> `(with-collectors (,@collectors ,collect-t)
> (dolist (l ,list)
> (cond ,@(mapcar (lambda (predicate collector)
> `((funcall ,predicate l) (,collector l)))
> predicates collectors)
> (t (,collect-t l)))))))
>
> An example:
>
> > (predicate-collect '(-5 -4 -3 -2 -1 0 1 2 3 4 5)
> (function evenp)
> (lambda (n) (< n 0))
> (lambda (n) (> n 3)))
> (-4 -2 0 2 4)
> (-5 -3 -1)
> (5)
> (1 3)
>
>
> I use the list collector macros by Tim Bradshaw here - see
> http://www.tfeb.org/lisp/hax.html#COLLECTING

Gauche Scheme

(define (multi-partition the-list . predicates)
(if (null? predicates)
(list the-list)
(receive (yes no)
(partition (car predicates) the-list)
(cons yes (apply multi-partition no (cdr predicates))))))

(multi-partition '(-5 -4 -3 -2 -1 0 1 2 3 4 5)
even?
(is < 0)
(is > 3))

((-4 -2 0 2 4) (-5 -3 -1) (5) (1 3))

Given:

(define-syntax is
(syntax-rules ()
[(is x)
(lambda (y) (equal? y x))]
[(is compare x)
(lambda (y) (compare y x))]
[(is key compare x)
(lambda (y) (compare (key y) x))]))