Re: Ann: SWI-Prolog 6.5.3

P.S. And there is actually no immediately obvious "sub_list" built-in list
predicate for efficient searching for (overlapping) substrings in a
list.... Or again, I have not paid enough attention when reading.


On Thu, Nov 21, 2013 at 3:10 PM, Boris Vassilev
<[email protected]>wrote:

>
> On Thu, Nov 21, 2013 at 12:45 PM, Jan Wielemaker <[email protected]>wrote:
>
>> The main point of strings is that they are *not* lists, so you know "ab"
>> is a string and not a list of two percentages ([97,98]). The NU Prolog
>> approach hides this detail, turning it only into an implementation
>> detail. Yes, you can represent any text as a SWI-Prolog atom. However,
>> this ignores the conceptual difference as well as the ability to exploit
>> runtime type information. There is also an important implementation
>> detail missing: atoms are expensive, in particular as a short-lived
>> datastructure. Nevertheless, we see that many applications do a lot of
>> sub_atom/5 and atom_concat/3 calls to do string manipulation with atoms.
>> Such applications tend to be slow, in particular if it concerns
>> multi-threaded servers. Most of these applications should be using the
>> list representation. Apparently many users do no like using lists for
>> text processing. I think one of the reasons is that it is often hard to
>> debug.
>>
>
>
> Starting without much experience with Prolog, and reading the manual, esp:
>
> http://www.swi-prolog.org/pldoc/man?section=strings
>
> "Although strings and atoms still have different features, new code should
> consider using atoms to avoid too many representations for text as well as
> for compatibility with other Prolog implementations."
>
> had led me to believe that I should, after all, be using atoms and not
> strings for representing text. Combined with not too many of the
> "established" Prolog tutorials/books even mentioning strings, it is not
> surprising that many applications use atoms with sub_atom/5 and
> atom_concat/3.
>
> If you actually think that strings are better suited for text you maybe
> should re-word the string section of the manual. (but this is probably
> happening anyway in V7?)
>
> Cheers,
> Boris
>
> --
> Boris Vassilev
> +358 9 191 25266
> Intracellular Cholesterol Trafficking Lab
> Institute of Biomedicine, Anatomy
> P.O. Box 63 (Haartmaninkatu 8)
> FI-00014 University of Helsinki, Finland
>



-- 
Boris Vassilev
+358 9 191 25266
Intracellular Cholesterol Trafficking Lab
Institute of Biomedicine, Anatomy
P.O. Box 63 (Haartmaninkatu 8)
FI-00014 University of Helsinki, Finland
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