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Re: updated draft



On Mon, Nov 25, 2013 at 9:38 AM, John Cowan <cowan@xxxxxxxxxxxxxxxx> wrote:
Alex Shinn scripsit:

> I answered this indirectly by expanding the history and making clear
> that the entire reason for using regular expressions is that they are
> efficient.  I have no intention of removing these warnings because
> this is a genuine security concern that programmers should be aware of.

There's a big difference between "prohibitively expensive" and "should
avoid their use" on the one hand, and "very expensive" and "should
avoid their use except when necessary" on the other.  I suggest the
latter language is more appropriate for a feature that is, after all,
being included, not excluded.

Expensive is the O(n^3) for the next step up the Chomsky hierarchy.
I think exponential warrants the use of "prohibitively."  The feature
is included mostly for completeness, for round-trip conversion from
existing PCRE libraries, and I think the advice that it should never
actually be used is warranted.

More importantly, while I appreciate your attention to editorial
detail, I think you need to lighten up.  We had to be very precise
for the core document because there were a lot of eyes on it and
people were very, very picky about exactly what went into it.
This is just a SRFI for a library, and I think a little opinion and dare
I say "color" from the authors should be allowed.

Right now what we want more than anything is people jumping
in and writing new SRFIs.  It's a tiring and thankless enough task
as it is without requiring that the prose be boring.

> > In <http://srfi.schemers.org/srfi-115/mail-archive/msg00020.html>,
> > Michael Montague requested textual alternate names for the patterns
> > ?, *, +, etc.  You agreed, but haven't done it.
>
> I said I see no reason not to do it.  If someone comes up with a
> reasonable list of names I can include them.

I propose `optional`, `zero-or-more`, `one-or-more`, `at-least`,
`exactly`, and `repeated`.  Verbose, but easy to understand.

And the same all prefixed with `non-greedy-' I suppose?
`non-greedy-one-or-more', ...

-- 
Alex