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From: Kevin Ryde <user42@zip.com.au>
Subject: srfi-13 string-any tail call
Date: Tue, 07 Dec 2004 08:08:23 +1100	[thread overview]
Message-ID: <871xe3yw1k.fsf@zip.com.au> (raw)

I'm thinking of the following wrapper around the string-any C code to
get a tail call on the last pred test, per the srfi-13 spec.  It's not
too pretty, but at least it'll be right.  I guess in the head it could
tie into eval now that string-any is in the core.

(define (string-any char_pred s . rest)
  (let ((start (if (null? rest)
                   0 (car rest)))
        (end   (if (or (null? rest) (null? (cdr rest)))
                   (string-length s) (cadr rest))))
    (if (and (procedure? char_pred)
             (> end start)
             (<= end (string-length s))) ;; let c-code handle range
             error
        (or (string-any-c-code char_pred s start (1- end))
            (char_pred (string-ref s (1- end))))
        (string-any-c-code char_pred s start end))))


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             reply	other threads:[~2004-12-06 21:08 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-12-06 21:08 Kevin Ryde [this message]
2004-12-22 16:54 ` srfi-13 string-any tail call Marius Vollmer
2004-12-22 21:30   ` Kevin Ryde
2004-12-23  4:16     ` Marius Vollmer

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