Re: [PATCH] add regexp-split

[Daniel Hartwig]

On 30 December 2011 21:23, Marijn <address@hidden> wrote:
> Group capturing is useful, but the question is whether it is useful in
> the context of regexp-split. Maybe it is, maybe it isn't. Racket seems
> to be doing it differently than python, so I think that constitutes
> reason to look more closely. Certainly guile should follow racket over
> python, everything else being equal, but usually everything isn't
> equal if only one has a look and I'm saying that we should look at
> least at other schemes for inspiration.
> If you're so convinced that python is doing it right here and should
> be followed, then perhaps you can give some examples of how capturing
> groups are useful in a function that is supposed to split strings at
> regexps.

Having the *option* to return the captured groups in `regexp-split' is
certainly useful -- consider implementing a parser [1].  If the
captured groups are not desired, then simply omit the grouping parens
from the expression.

[1] http://80.68.89.23/2003/Oct/26/reSplit/

>
> Another data point:
>
> [14:17] <hkBst> what does chicken return for (irregex-split "([^0-9])"
>  "123+456*/")  ?
> [14:18] <sjamaan> ("123" "456")
>
> Looks like chicken doesn't do capturing groups in their version, but
> they don't have the empty matches either. How about that...

For tokenizing I think you want to keep any empty strings, otherwise
you lose track of which `field' you are in (consider /etc/passwd
entries).  This also matches the existing behaviour of `string-split'.