Subject: Re: Revisiting split-sequence and patterns
From: Erik Naggum <>
Date: Sat, 01 Dec 2001 13:30:57 GMT
Newsgroups: comp.lang.lisp
Message-ID: <>

* Jeff Greif
| I'm not sure your reason is strong enough to allow such a line to fall
| outside the usage of this new split-sequence functionality.

  I am.  You need a real parser, not just a "split" function to get this
  kind of functionality.  OK, I called my function "parse-delimited-list"
  and that was probably misleading, but if we do this, it will grow into a
  full-fledged programmable parser like the Common Lisp reader, and then it
  is a better project to make the reader more powerful.  (I am working on
  that, too, in particular to get a handle on the function that decides
  when something is a symbol.)

| It might be useful to add one more syntax pattern -- characters that are
| punctuation (delimit tokens) but also *are* tokens (unless escaped or
| appearing inside the multiple escaped sequence).  Using that pattern,
| the line above could be tokenized as ( "[" "Wed" "Oct" "11" ... "]" ...)
| and a higher level of parsing could handle the rectangular brackets.

  I think this is a much better design.  There is but one drawback, which
  may be a feature, and that is that you no longer have any special rules
  inside the delimiter pairs, which I would kind of expect for a language
  that uses matching delimiters.

  The past is not more important than the future, despite what your culture
  has taught you.  Your future observations, conclusions, and beliefs are
  more important to you than those in your past ever will be.  The world is
  changing so fast the balance between the past and the future has shifted.