Re: about dynamic/1 and file format

On 01/06/2014 02:31 PM, Jiun-Shiung Wu wrote:
> Hi, Jeff,
>
> Thank you very much for your response. As for dynamic, I am talking about
> the second one in your response. Because I am trying to establish a
> knowledge base in which new facts can be added, I declare :-

Have a look at library(persistency):

http://www.swi-prolog.org/pldoc/doc/home/vnc/prolog/lib/swipl/library/persistency.pl

That library provides a fairly robust way to make a dynamic
predicate persistent by maintaining a journal file that contains
Prolog terms.  AFAIK, it always uses UTF-8 encoding to be locale
independent.

	Cheers --- Jan

P.s.	:- dynamic(foo/1). and
	:- dynamic foo/1. are simply the same.  The only sensible
	reason to use the first is that some Prolog systems do not
	declare dynamic as an operator.  You can remove the operator
	declaration for SWI-Prolog using ?- op(0, fx, dynamic). or
	add it to the other Prolog using ?- op(1100, fx, dynamic).

> dynamic(father/2) at the beginning of my file. When I write all of the
> father/2 facts into a new file, I get :- dynamic father/2 at the beginning
> of my new file. When I try my program again, :- dynamic father/2 does not
> work. So, is there a way to put the parentheses back?
>
> As for file format, I used open/4 and I did specify the file format to be
> UTF-8. But, I opened the file with Notepad++, it showed that the file was
> the format of UTF-8 without the BOM header. So....
>
> Best,
>
> Hunter
>
> ------------------------------------------------------
> Wu, Jiun-Shiung, Ph.D.
> Professor
> Institute of Linguistics
> National Chung Cheng University
> 168, University Road,
> Minhsiung, Chiayi County,
> Taiwan 621
> -------------------------------------------------------
>
>
> 2014/1/6 Jeff Rosenwald <[email protected]>
>
>> Hi Hunter:
>>
>> On the business of dynamic predicates, it is not entirely clear what you
>> are trying to accomplish.
>>
>> There are two syntaxes for "dynamic" predicates: 1) as a directive (usage
>> in the body of a headless predicate), and 2) as an ordinary predicate used
>> in the body of a named predicate. The first provides for compile-time
>> declaration of dynamic predicates and in that case, the grammar allows you
>> to specify one or more name/arity combinations separated by commas. There
>> are no parentheses. The second syntax provides for run-time declaration of
>> dynamic predicates. It is structured as an ordinary predicate and allows
>> exactly one name/arity compound as an argument. I believe that the
>> postcondition is the same regardless of the form used.
>>
>> When writing a text file using Prolog streams, you can specify the
>> encoding of the file using the type(text) and encoding/1 options of open/3.
>> I believe that you can also use set_set_stream_property/2 as well. When
>> writing files (using external editors and such) that you wish to eventually
>> consult with SWIPL, you may supply an encoding/1 directive as the first
>> line of the file.
>>
>> Regards,
>> Jeff R.
>>
>>
>>
>>   -----Original Message-----
>> From: Jiun-Shiung Wu <[email protected]>
>> To: swi-prolog <[email protected]>
>> Sent: Mon, Jan 6, 2014 7:22 am
>> Subject: [SWIPL] about dynamic/1 and file format
>>
>>   Hi, SWI-Prolog users,
>>
>> I have two questions concerning dynamic/1 and saved file format. I am
>> wondering if someone can help me.
>>
>> I used dynamic to declare that a predicate is dynamic. For example, I put
>> :- dynamic(father/2) at the beginning of my file. I used listing(father/2)
>> to list all instances of father/2. I found that the parentheses in dynamic
>> is gone. That is, when I did listing(father/2), I got: dynamic father/2.
>> When I used with_input_to to save all instances of father/2, I got :-
>> dynamic father/2 at the beginning of the new file. The parentheses are
>> missing. Is there a way not to remove the parentheses in this case?
>>
>> Secondly, how can I save a file using the UTF-8 with the header BOM? I have
>> a knowledge base containing facts written in traditional Chinese (UTF-8).
>> When I used with_input_to to save those facts into a new file, the BOM head
>> seems to be gone and my Prolog program cannot read it. Though it is easy to
>> restore the BOM head using Notepadd++, I am still wondering whether
>> SWI-Prolog can save a file using UTF-8 with the BOM head.
>>
>> Thank you!
>>
>> Hunter Wu
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