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devel / comp.lang.lisp / .Re: Incredibly stupid newbie question

.Re: Incredibly stupid newbie question

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https://www.rocksolidbbs.com/devel/article-flat.php?id=16955&group=comp.lang.lisp#16955

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From: No_spamming@noWhere_7073.org (Robert L.)
Newsgroups: comp.lang.lisp
Subject: .Re: Incredibly stupid newbie question
Date: Sun, 13 Mar 2022 05:24:34 -0000 (UTC)
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by: Robert L. - Sun, 13 Mar 2022 05:24 UTC

Kaz Kylheku wrote:

> For instance, there is the REDUCE function which will decimate a
> sequence through a binary operator.
>
> (reduce (lambda (left right) (concatenate 'string left ", " right))
> #("a" "b" "c"))
>
> => "a, b, c"

Gauche Scheme:

(reduce
(& string-append v ", " u)
#f
'("a" "b" "c"))

===>
"a, b, c"

Given:

(define-syntax &-aux
(syntax-rules (u v w quote)
[(_ () shadow (param ...) original)
(lambda (param ...) original)]
[(_ (u more ...) (x y ...) () original)
(&-aux original original (x) original)]
[(_ (v more ...) (x y ...) (a) original)
(&-aux original original (a x) original)]
[(_ (w more ...) (x y ...) (a b) original)
(&-aux () () (a b x) original)]
[(_ ((quote ...) more ...) (y z ...) params original)
(&-aux (more ...) (z ...) params original)]
[(_ ('x more ...) (y z ...) params original)
(&-aux (more ...) (z ...) params original)]
[(_ ((s ...) more ...) (y z ...) params original)
(&-aux (s ... more ...) (s ... z ...) params original)]
[(_ (x more ...) (y z ...) params original)
(&-aux (more ...) (z ...) params original)]
))
;; Lambda with anaphoric parameters u, v, and w.
(define-syntax &
(syntax-rules ()
[(& x ...)
(&-aux (x ...) (x ...) () (x ...))]))

Subject	Author
.Re: Incredibly stupid newbie question	Robert L.