Re: regexp-split for Guile

[Thien-Thi Nguyen <ttn@gnuvola.org>]

[-- Attachment #1: Type: text/plain, Size: 2072 bytes --]

() "Chris K. Jester-Young" <cky944@gmail.com>
() Mon, 17 Sep 2012 10:01:33 -0400

   (define (string-empty? str)
     (zero? (string-length str)))

You can use ‘string-null?’ instead.

   (define* (regexp-split pat str #:optional (limit 0))
     (let* ((result (fold-matches pat str '(0) regexp-split-fold 0
                                  (if (positive? limit) (1- limit) #f)))
            (final (cons (substring str (car result)) (cdr result))))
       (reverse! (if (zero? limit) (drop-while string-empty? final) final))))

Style nit: i find it easier to read ‘if’ expressions w/ the condition,
then and else expressions on separate lines.  Similarly ‘cons’.  E.g.:

(define* (regexp-split pat str #:optional (limit 0))
  (let* ((result (fold-matches pat str '(0) regexp-split-fold 0
                               (if (positive? limit)
                                   (1- limit)
                                   #f)))
         (final (cons (substring str (car result))
                      (cdr result))))
    (reverse! (if (zero? limit)
                  (drop-while string-empty? final)
                  final))))

It is easier because the eye can flowingly bump along the indentation
w/o the doubtful mind jerking it to the right to fully identify and then
verify forks and merges.  Does that make sense?  (If not, just ignore.)

A more substantial line of questioning: What happens if ‘regexp-split’
is called w/ negative ‘limit’?  Should that be handled in ‘regexp-split’
or will the procs it calls DTRT?  What is TRT, anyway?  In the absence
of explicit validation, maybe a comment here will help the non-expert.

-- 
Thien-Thi Nguyen ..................................... GPG key: 4C807502
.                  NB: ttn at glug dot org is not me                   .
.                 (and has not been since 2007 or so)                  .
.                        ACCEPT NO SUBSTITUTES                         .
........... please send technical questions to mailing lists ...........


[-- Attachment #2: Type: application/pgp-signature, Size: 197 bytes --]