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Re: ANN: SRFI 155: Scheme Regular Expressions

This page is part of the web mail archives of SRFI 115 from before July 7th, 2015. The new archives for SRFI 115 contain all messages, not just those from before July 7th, 2015.

On Tue, Oct 15, 2013 at 2:47 PM, Arthur A. Gleckler <scheme@xxxxxxxxxxxxxx> wrote:
This SRFI is a tour de force.  Nice job.

I have just a few small comments:

* In the description of `regexp-fold', in "...calls finish with the same argument," the word "argument" should be plural.

* In the paragraph describing `rx-match-submatch', the sentence beginning "if an integer outside..." is confusing.  I suggest changing it to "If passed an integer outside the range of matches, or a symbol which does not correspond to a named submatch of the pattern, it is an error."

* The phrase "desirable to want to" should just be "desirable to."

Fixed these.

* I agree that <- would be a better choice than =>.  Perhaps now is the time to make the change before SRFI 115 is set in stone.  There's a great story from the original author of Make.  He said that he decided early on that he couldn't reverse the decision to make SPC and TAB have different meanings -- a terrible decision -- because he already had ten users!

IrRegex has quite a lot more users.  It's the builtin regexp
engine for Chicken, and is used in a number of other
implementations.  It's harder to say how many people just
use it for PCRE-style regexps, and how many actively
use the SRE notation.

But we can still consider changing it.  I had written <-
thinking of a syntax:

  name <- pat

without any parens (you'd need an explicit (: ...) wrapper
in some cases), but this complicates parsing and there
are many advantages to sticking to a pure prefix notation.
So better would be

  (-> name pat ...)