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Re: [bigloo] behavior of CASE with strings
- From: Per Bothner <per at bothner dot com>
- To: Damien Mattei <damien dot mattei at gmail dot com>, Bent Phillipsen <bent dot phillipsen at gmail dot com>
- Cc: Kawa mailing list <kawa at sourceware dot org>, bigloo at sophia dot inria dot fr
- Date: Sat, 21 Jan 2017 08:54:24 -0800
- Subject: Re: [bigloo] behavior of CASE with strings
- Authentication-results: sourceware.org; auth=none
- References: <201701121129.54147.Damien.Mattei@unice.fr> <2017116143211.587ccb5b@redrock.inria.fr> <CAD1yAURxqeVTmpbktQr-+F6hKZUySg6zQbRzjB224=wTvfNa-w@mail.gmail.com> <CADEOadf+++LDz8srLL2p3Vh6hgpjMiqF2-g1-O2_7K9bp1eGEw@mail.gmail.com>
On Tue, Jan 17, 2017 at 8:27 PM, Bent Phillipsen <bent.phillipsen@gmail.com> wrote:
This has the consequence that stings cannot be used as key and clause in
case expressions in a well defined way (or at least portable way). You can
however easily define a macro that *also* can use strings. You can write
your own; but simply taking the case macro defined in R5RS (p.43) ensures
that all corner cases are handled correctly. You then just need to replace
'memv' with 'member' (this has the effect of testing equivalence with equal?
instead of eqv?). You probably want to change the name of the macro also,
for instance to case-member, to avoid shadowing the original case
expression. You will get something like the following, which should work and
which I think is portable. (There is of cause a (mostly insignificant)
performance penalty in testing with equal? instead of eqv?):
In Kawa 'case' is optimized, so the performance penalty of re-implementing
case "by hand" would be more significant.
--
--Per Bothner
per@bothner.com http://per.bothner.com/