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comp.lang.lisp

Re: qsort optimized for brevity

William James

9/26/2015 8:47:00 PM

> (defun partition (list &aux (pivot-value (first list)))
> (loop for item in list
> if (< item pivot-value)
> collect item into less
> else
> collect item into greater-or-equal
> finally (return (values less greater-or-equal))))
>
> Never underestimate the power of LOOP :)

Gauche Scheme:

gosh> (partition odd? '(2 0 9 4 3 6))
(9 3)
(2 0 4 6)

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2 Answers

William James

10/13/2015 6:20:00 AM

0

WJ wrote:

> > (defun partition (list &aux (pivot-value (first list)))
> > (loop for item in list
> > if (< item pivot-value)
> > collect item into less
> > else
> > collect item into greater-or-equal
> > finally (return (values less greater-or-equal))))
> >

Portable Standard Lisp:

(load numeric-ops)

(de partition (list)
(let (less gte)
(foreach item in list do
(if (< item (car list))
(push item less)
(push item gte)))
(mapcar (list less gte) #'reverse)))

4 lisp> (partition '(5 4 7 8 0))
((4 0) (5 7 8))

William James

10/29/2015 9:04:00 AM

0

WJ wrote:

> > (defun partition (list &aux (pivot-value (first list)))
> > (loop for item in list
> > if (< item pivot-value)
> > collect item into less
> > else
> > collect item into greater-or-equal
> > finally (return (values less greater-or-equal))))
> >
> > Never underestimate the power of LOOP :)
>
> Gauche Scheme:
>
> gosh> (partition odd? '(2 0 9 4 3 6))
> (9 3)
> (2 0 4 6)

MatzLisp (Ruby):

[2,0,9,4,3,6].partition &:odd?
==>[[9, 3], [2, 0, 4, 6]]

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