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Re: ANN: SRFI 155: Scheme Regular Expressions

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 ...)