Re: [eclipse-users] Library Induction

On Thursday 26 April 2007 03:24, Siddharth Angrish wrote:
>            Thanks for the previous comments. I have the following
> queris/points to make:
> 
> 1) As per your suggestion I am installing sicstus on my machine and
> paralelly try to
> see if there some advantages.
> 
> 2) During FSA6 installation, the type of Prolog available on machine is asked.
> The fsa_library and other supporting libraries are generated
> afterwards. It appears
> that FSA6 generates all its libraries according to the Prolog
> available. Hence, FSA6
> might be treating all Prologs as same.
> 
> 3)   I have installed ECLiPSe 5.10 on my machine. I noticed this
> peculiar thing, the path
>   had to be encloed in "`", that is, backticks rather than double
> quotes while in previous
> ECLiPSe double quotes were used. Is this some fancy change or I am
> seeing strange
> behaviour?

This is not a change in ECLiPSe 5.10, but instead is because you loaded lib(swi), and what you
see is the SWI syntax:

In ECLiPSe, strings are enclosed in double quotes: "string", but in most other Prologs, this 
represents a list of numbers, where each number represents the ASCII value of the characters
in the string. When you load lib(swi), ECLiPSe is switched to using this representation, so
you can no longer use double quotes to represent strings.

In SWI, strings are represented using the backquotes character you mentioned, and once you
loaded (imported) lib(swi), the module you are using supports this syntax as well.


> I used the following command:
>   get_flag(library_path,Path),
>         set_flag(library_path, [`/users/angrish/fsa/fsa6/swi` | Path]).
> 
> 4)  The above added path has all the required libraries. After adding
> this path I get the
> following error upon executing lib(fsa_library):
> --------------------------------------------
> lib(fsa_library).
> calling an undefined procedure use_module(charsio, [format_to_chars /
> 3]) in module eclipse
> 
> *** compilation aborted
>         before line 24 in the file /users/angrish/fsa/fsa6/swi/fsa_library.pl
> Abort
> ---------------------------------------------
> 
> This appears to be due to incompatibility between ECLiPSe and SWI Prolog.

Yes. 

> What are the possible remedies for this? Shall I try changing this paticular
> "use_module" to the one compatible with ECLiPSe. There a total of 35 such usages
> in all the libraries.

A proper fix would be to use ensure_loaded/1 followed by import/1 (import ... from ...).

However, this is one thing that could (should?) be supported by lib(swi) -- the use_module/2
syntax is supported by lib(quintus) and lib(sicstus), so it probably should be supported by
lib(swi) as well.  

I think you can add support for use_module/2 to your copy of swi.ecl, by adding use_module/2
to the list of predicates exported from the quintus module. Change

:- reexport
	(multifile)/1, op(_,_,(multifile)),
	format/2,
	format/3
    from quintus.

to

:- reexport
	(multifile)/1, op(_,_,(multifile)),
        use_module/2,
	format/2,
	format/3
    from quintus.

in the swi.ecl file. If you have a binary distribution, this file is in <ECLiPSe>/lib/swi.ecl. You 
also need to remove the compiled swi.eco file in the same directory, so that swi.ecl will be
loaded instead of swi.eco, which is the compiled form of the original swi.ecl file (i.e. without
the above change). 

>       What I am afraid of is if after this change I run into more such
> incompatibilites?
> Is there some cheaper way?
>

You may very well run into more incompatibilities, some of which may be things (like 
use_module/2) that can be easily added to lib(swi). 

Cheers,

Kish