Re: [eclipse-clp-users] Calling predicates from a module using Java

From: Wit Jakuczun <wit.jakuczun_at_...6...>
Date: Wed, 28 May 2008 09:04:46 +0200
Thank you for the answer. I have realised my stupid mistake a minute
after sending  a post to a group.

By the way I would like to clarify another issue.
Suppose I have a predicate: test.
1) test has arity 1:
  test(V) :- V is 1.
  Now using rpc:
  CompoundTerm ret = engine.rpc(
                                                new CompoundTermImpl(
           "test",
            null)
   );

  does not work. I get a following exception
com.parctechnologies.eclipse.CompoundTermImpl.<init>(CompoundTermImpl.java:68)

2) Having test defined as follows:
  test(V, N)  :- V is 1.
  the following Java code works:
  CompoundTerm ret = engine.rpc(
                                                new CompoundTermImpl(
           "test",
            null,
            new Integer(3))
   );

Why 1) throws an exception and 2) does not? I would like
to have a predicate defining variable, that is of arity 1 ( like test(V)  ).

Best regards
[ Wit Jakuczun w.jakuczun@...116... ]
[ WLOG Solutions http://wlogsolutions.com   ]


2008/5/27 Kish Shen <kish@...2...>:
> Hi,
>
> Wit Jakuczun wrote:
>>
>> Hi,
>>   I have a question regarding Java to ECLiPSe interface.
>> I have a prolog program that consists of a few modules.
>> I would like to be able to call a predicate from a module.
>> For this I tried such code:
>>        CompoundTerm ret = engine.rpc(
>>                new CompoundTermImpl(":",
>>                        "problem",
>>                        "test(V)"
>>                        )
>>                );
>>
>> Unfortunately it does not work. I get the following error:
>>    type error in type error in is_a_module("problem")
>>
>>
>
> You are using Java strings for "problem" and "test(V)". These are mapped to
> ECLiPSe strings -- see the section on the mapping between ECLiPSe and Java
> data types in the Embedding manual. ECLiPSe modules
> have to be atoms, not strings -- this is why you are getting the type error
> (and also "test(V)" is a string, and not
> the compound term test(V)).
>
> Cheers,
>
> Kish
>
>> Of course earlier I have apriopriate
>> engine.rpc("use_module(\"problem.ecl\")");
>>
>> Moreover I can call a predicate from a module using C interface.
>>
>> I would be grateful for any explanation.
>>
>> Best regards
>> --
>> [ Wit Jakuczun w.jakuczun@...116... ]
>> [ WLOG Solutions http://wlogsolutions.com   ]
>>
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>
Received on Wed May 28 2008 - 00:04:51 CEST

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