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1 point by almkglor 6171 days ago | link | parent

Note also that for simple parsing needs, using scanners may be "good enough". For example:

  (require "lib/scanner.arc")
  (def lines-from-scanner (s)
    (drain
      (when s
        (tostring
          ; doesn't handle Mac text files though...
          (while (aand (car s) (if (isnt it #\newline)
                                   (write it)))
            (zap cdr s))))))
  (def lines-from-file (f)
    (w/infile s f
      (lines-from-scanner (scanner-input s))))


2 points by akkartik 6162 days ago | link

It seems like:

  (zap cdr s)
doesn't work when s is a scanner -- s remains unchanged. I looked at the code and convinced myself that macros like zap that call setforms won't work for new types. Does that make sense?

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2 points by almkglor 6162 days ago | link

  arc> (require "lib/scanner.arc")
  nil
  arc> (= s (scanner-string "asdf"))
  #3(tagged scanner (#<procedure> . #<procedure>))
  arc> (car s)
  #\a
  arc> (zap cdr s)
  #3(tagged scanner (#<procedure> . #<procedure>))
  arc> (car s)
  #\s

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1 point by akkartik 6167 days ago | link

Hmm, just saw this. Thanks for the tip.

I'll work on this some more this weekend, and hopefully have something cogent to say.

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