Re: [swipl] Use arithmetic_function/1 inside a module

On Tue, Apr 1, 2014 at 7:16 PM, Jochem Liem <[email protected]> wrote:
> Why are you using: 'X is xsd_div(7, 2).' ?
> You can just do 'test_arithmetic:xsd_div(7,2,X)'.
But then it's no longer a function? I want nested expressions to
evaluate out-of-the-box like the swipl builtin arithmetic functions
do. For example:
~~~{.pl}
TimeOnTimeline is
    % Year
    31536000 * Y2
    % Leap-year days
    + 86400 * (Y2 xsd_div 400 - Y2 xsd_div 100 + Y2 xsd_div 4)
    % Month
    + 86400 * D3
    % Day
    + 86400 * D2
    % Hour
    + 3600 * H2
    % Minute
    + 60 * MM3
    % Second
    + S2.
~~~

(PS: For these examples is could use the builtin function div i.o.
xsd_div, but I want to be able to define different functions as well.)

Cheers,
Wouter.
>
> ?- test_arithmetic:xsd_div(7,2,X).
> X = 3.
>
> Cheers,
> Jochem
>
> On Tue, Apr 1, 2014 at 8:00 PM, Wouter Beek <[email protected]> wrote:
>> Hi list,
>>
>> Is it possible to define an arithmetic function inside a module?
>>
>> Sample file:
>> ~~~{.pl}
>> :- module(test_arithmetic_1, []).
>> :- use_module(library(arithmetic)).
>> :- arithmetic_function(xsd_div/2).
>> xsd_div(X, Y, Z):-
>>   Z is floor(X / Y).
>> ~~~
>>
>> Usage:
>> ~~~
>> swipl -s test_arithmetic_1.pl
>> ?- X is xsd_div(7, 2).
>> Error: Arithmetic: `xsd_div(7,2)' is not a function
>> ~~~
>>
>> I have no problem with using arithmetic functions defined in non-module files.
>>
>> ---
>> Cheers!,
>> Wouter.
>>
>> E-mail: [email protected]
>> WWW: www.wouterbeek.com
>> Tel.: 0647674624
>> _______________________________________________
>> SWI-Prolog mailing list
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>
>
>
> --
> Jochem Liem, PhD
> http://jochemliem.wordpress.com
>