Re: [eclipse-clp-users] Question regarding null variable

Hi Kish

Thank you for your time and explanation.
This will surely help me move ahead.

Will surely keep learning ECLiPSe from the documentation links.

Regards

Yogesh
________________________________________
From: Kish Shen [kisshen_at_cisco.com]
Sent: 15 December 2014 19:27:18
To: Choughule, Yogesh; eclipse-clp-users_at_lists.sourceforge.net
Subject: Re: [eclipse-clp-users] Question regarding null variable

Hi Yogesh,

On 15/12/2014 08:32, Choughule, Yogesh wrote:
> Hi Kish
>
> I will explain null in Java context because i am trying to solve java code using ECLiPSe.
> for e.g.
> Integer x = null;
> In Java, null means variable x does not refer to any value in memory.
>

Prolog variables are quite different conceptually from variables in
conventional programming languages. As Matthew said, Prolog variables
are like variables in mathematics, in that they represent (as yet)
unknown values when they are not instantiated. So conceptually, a
variable is not a memory location to which you can assign values. This
'variable as memory location' is made explicit in Java's null, and does
not make sense in Prolog.

I am not sure what you mean by 'solve java code using ECLiPSe', but it
does not look trivial and will probably involve a significant amount of
programming in ECLiPSe, so again I suggest you should learn
Prolog/ECLiPSe first.

Cheers,

Kish



> In Prolog, we write something like
> X $= 2,
>
> So in Prolog, i want to know if i can specify something like
> X $= null,
>
> if not, is there any similar concept which can be used as null in any of the libraries supported by ECLiPSe?
>
> Regards
>
> Yogesh
>
> ________________________________________
> From: Kish Shen [kisshen_at_cisco.com]
> Sent: 15 December 2014 17:00:58
> To: Choughule, Yogesh; eclipse-clp-users_at_lists.sourceforge.net
> Subject: Re: [eclipse-clp-users] Question regarding null variable
>
> Hi Yogesh,
>
> I think you need to give more context and explain what you mean by
> 'null'. ECLiPSe supports several constraint solver libraries -- so you
> need to say the library you are talking about for the 'constraint' you
> mentioned, and what exact effect 'null' has when 'specified as a
> constraint'.
> Cheers,
>
> Kish
>
> On 15/12/2014 01:52, Choughule, Yogesh wrote:
>> Dear Users
>>
>> My questions is regarding the usage of null variable.
>>
>> 1) Can we specify a variable as null in ECLiPSe?
>> I am trying to implement a functionality where null needs to be specified as a constraint.
>>
>> 2)if not, is there any workaround to represent null in ECLiPSe?
>>
>> Thanks and Regards
>>
>> Yogesh C.
>>
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______________________________________________________________________
Disclaimer: This email and any attachments are sent in strictest confidence
for the sole use of the addressee and may contain legally privileged,
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please advise the sender by replying promptly to this email and then delete
and destroy this email and any attachments without any further use, copying
or forwarding.