I found it….
Section 6.2 Types and Modes, in the table…
character a single character atom
and from the preceding table entry:
TYPE_list a list whose the type of each element is TYPE
So I guess it was there after all I just didn't see it. What a surprise.
On 4 Jul 2013, at 09:23, Daniel Diaz <[email protected]> wrote:
> Le 03/07/2013 18:30, emacstheviking a écrit :
>> Can somebody point me to to the docs where it says "single character atoms
>> are characters" please....
>
> You are right, from the Prolog programmer point of view, a character is an
> atom of length 1.
>
> Unfortunately the gprolog doc does not define the syntax of Prolog terms
> since gprolog conforms to the ISO standard for Prolog (ok I should add it).
> Lower case letters can be written unquoted (e.g. a, b, ...) orther chars need
> to be quoted (e.g. '#', 'A', ...).
>
> Daniel
>
>> I seem to have missed something basic. I will also read LPN, C&M and Art of
>> Prolog tonight and make sure I take it in that atoms are also characters.
>>
>> Dammit.
>> :(
>>
>>
>> On 3 July 2013 16:26, Daniel Diaz <[email protected]> wrote:
>> Le 03/07/2013 16:44, emacstheviking a écrit :
>>> Hi,
>>>
>>> I have been experimenting with the foreign interface and managed to confuse
>>> myself.
>>>
>>> Given this foreign declaration:
>>>
>>> %% :- foreign( foo( +string ), [fct_name( foo )]). %% +string => atom at
>>> call site
>>> %% :- foreign( foo( +codes ), [fct_name( foo )]).
>>>
>>> :- foreign( foo( +codes ), [fct_name( foo )]).
>>>
>>> and this implementation:
>>>
>>> // +string :: atom ==> char*, works
>>> // +codes :: character-code list ==> char*, works as foo("Hello").
>>> // +chars :: character list ==> char*, fails on call foo("HI"),
>>> foo([64,65]). Why?
>>>
>>> PlBool
>>> foo(char* s)
>>> {
>>> printf("FOO: ==> %s\n", s);
>>> return PL_TRUE;
>>> }
>>>
>>> My problem is that when I use "+chars" I can't then say:
>>>
>>> foo("Hello")
>>>
>>> as I get a type_error so please can anybody explain to me what "character
>>> list" is and how it looks in a command line session? The flag that controls
>>> the interpretation of double-quoted strings is at its default value as I
>>> have not altered it but I am aware of its existence and the fact that "" is
>>> syntactic sugaring of lists of codes.
>> Hi,
>>
>> +atom means you pass an atom (e.g. abc) and you get the internal reference
>> of the atom in C (which is an integer)
>> +chars means you pass a list of characters (e.g. [a,b,c]) and you get a NULL
>> terminated string in C, ie. a char * (e.g. "abc")
>> +code means you pass a list of char codes (e.g. [97,98,99] which is the same
>> a "abc" in Prolog) an dyou get the same char * as above.
>>
>> See http://gprolog.univ-paris1.fr/manual/html_node/gprolog068.html
>>
>> Daniel
>>
>>
>>>
>>> Thanks.
>>>
>>>
>>> --
>>> Ce message a été vérifié par MailScanner pour des virus ou des polluriels
>>> et rien de suspect n'a été trouvé.
>>>
>>> _______________________________________________
>>> Users-prolog mailing list
>>> [email protected]
>>> https://lists.gnu.org/mailman/listinfo/users-prolog
>>
>>
>> --
>> Ce message a été vérifié par MailScanner pour des virus ou des polluriels et
>> rien de suspect n'a été trouvé.
>>
>>
>> --
>> Ce message a été vérifié par MailScanner pour des virus ou des polluriels et
>> rien de suspect n'a été trouvé.
>
>
> --
> Ce message a été vérifié par MailScanner pour des virus ou des polluriels et
> rien de suspect n'a été trouvé.
_______________________________________________
Users-prolog mailing list
[email protected]
https://lists.gnu.org/mailman/listinfo/users-prolog
