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Re: help to get this running faster

From: David Pirotte
Subject: Re: help to get this running faster
Date: Tue, 05 Sep 2000 12:27:43 +0200

Mikael Djurfeldt wrote:
> ...
> 1. The support for optional arguments is currently slow.  Don't use
>    this in inner loops.
> 2. Guile's implementation of continuations is heavy.  Again, avoid
>    this in inner loops.
> 3. `read-line' is currently an interpreted Scheme closure.  We should
>    optimize this, but haven't got to it yet.  If you can use the
>    low-level %read-line as a temporary kludge, this will speed up your
>    code.

Many thanaks to all suggestions, here is what I did:

can someone give me a little example on how I could get precise figures on
execution time, cons ...


;; -- module (alto tabreader)

(define-module (alto tabreader))

(export char-pos

;; (use-modules (ice-9 optargs))
;; (use-modules (ice-9 format))

(define (char-pos char str start end)
  ;; (format #t "Char:  ~A~%Str:        ~A~%Start:      ~A~%End:        ~A~%"
  ;; char str start end)
  (catch 'exit
         (lambda ()
           (do ((i start (+ i 1)))
               ((>= i end) #f)
             (if (char=? (string-ref str i) char)
                 (throw 'exit i))))
         (lambda (key index)

;; (char-pos #\tab "david       pirotte")

(define (get-tokens str sep)
  (let ((tokens '())
        (start 0)
        (str-len (string-length str)))
    (do ((end (char-pos sep str start str-len)))
        ((not end)
         (reverse! (cons (substring str start str-len) tokens)))
      (set! tokens (cons (substring str start end) tokens))
      (set! start (+ 1 end))
      (set! end (char-pos sep str start str-len)))))

;; (get-tokens "david   pirotte musician")

(define (load-records fname field-sep)
  (call-with-input-file fname
    (lambda (i-stream)
      (do ((records '())
           (line (%read-line i-stream) (%read-line i-stream)))
          ((eof-object? (car line)) (reverse! records))
        (set! records (cons (get-tokens (car line) field-sep)

;; (load-records "/usr/alto/projects/postgres/" #\tab)
;; (load-records "/usr/alto/projects/psion/revo/backup/palm-adresses.txt" #\tab)

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