Re: behavior of CASE with strings

Hi Per,

Yes, you are of cause right: the performance penalty is also due to the use
of macro-case instead of build-in case – and in fact it is the largest part
using bigloo.

Out of curiosity I did a small test with bigloo, looping 10 Mio times over
a case expression (that cannot be optimized away by the compiler). The
runtime increase with macro case and member is about 100%. Only about 25%
of the runtime increase is due to the use of member instead of memv.

For most applications these performance differences are probably not
relevant.

Best regards

Bent



2017-01-21 17:54 GMT+01:00 Per Bothner <[email protected]>:

> On Tue, Jan 17, 2017 at 8:27 PM, Bent Phillipsen <
> [email protected]> 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
> [email protected]   http://per.bothner.com/
>