novaBBS - comp.lang.forth - Re: Grouping elements in a list

Grouping elements in a list

<t00pt4$14b$1@gioia.aioe.org>

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From: No_spamm...@noWhere_7073.org (Robert L.)
Newsgroups: comp.lang.forth
Subject: Grouping elements in a list
Date: Sat, 5 Mar 2022 22:57:42 -0000 (UTC)
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by: Robert L. - Sat, 5 Mar 2022 22:57 UTC

Group adjacent equal items in a list.

Gauche Scheme and Racket:

;; for Racket only
(require srfi/1) ;; fold-right

(define (kons x accum)
(if (or (null? accum) (not (equal? x (caar accum))))
(cons (list x) accum)
(cons (cons x (car accum)) (cdr accum))))

(define (group lst)
(fold-right
kons
'()
lst))

(group '(foo bar bar j j j k baz baz))

===>
((foo) (bar bar) (j j j) (k) (baz baz))

In Forth?

Re: Grouping elements in a list

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Subject: Re: Grouping elements in a list
From: sdwjac...@gmail.com (S Jack)
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by: S Jack - Sun, 6 Mar 2022 00:53 UTC

On Saturday, March 5, 2022 at 4:57:45 PM UTC-6, Robert L. wrote:
> Group adjacent equal items in a list.
>
> Gauche Scheme and Racket:
>
> ;; for Racket only
> (require srfi/1) ;; fold-right
>
> (define (kons x accum)
> (if (or (null? accum) (not (equal? x (caar accum))))
> (cons (list x) accum)
> (cons (cons x (car accum)) (cdr accum))))
>
> (define (group lst)
> (fold-right
> kons
> '()
> lst))
>
>
> (group '(foo bar bar j j j k baz baz))
>
> ===>
> ((foo) (bar bar) (j j j) (k) (baz baz))
>
>
> In Forth?
:) frogd
ELF32X86_64 Frog Version 1.0d

"job" /go
{ 0 pad !
begin
bl parse dup while ( have item )
2dup pad gscmp if ( a new item )
pad @ if ." )" fi
cr ." ( "
fi
2dup pad gts
type space
repeat
." )"
} run1 foo bar bar j j j k baz baz
( foo )
( bar bar )
( j j j )
( k )
( baz baz ) ok
bye :)
--
me

Work continues in this area. -- DEC's SPR-Answering-Automaton

devel / comp.lang.forth / Re: Grouping elements in a list

Subject	Author
Grouping elements in a list	Robert L.
Re: Grouping elements in a list	S Jack