Re: Suggestions for dcg_basics

On 10/17/2013 02:56 AM, Richard A. O'Keefe wrote:
>
> On 16/10/2013, at 8:53 PM, Boris Vassilev wrote:
>
>> There is one small detail about string//1 that bothers me, probably because
>> I don't understand how to use it properly:
>>
>> in its current implementation, it takes as few tokens as possible, and
>> takes more on backtracking.  So, for a n-token string, it will fail and
>> backtrack n-1 times.
>
> The definition is just
>
>      string([]) -->
>          [].
>      string([X|Xs]) -->
>          [X],
>          string(Xs).
>
> (By the way, string//1 is a *bad* name for this predicate because it is
> *NOT* in any way restricted to strings.  It will match a list of XML
> elements as happily as anything else.  And yes, it does make a lot of
> sense to use DCG with sequences of XML terms.)

Not sure I agree here.  The library as a whole is defined to do 
meaningful things with strings of character codes, such as parsing
numbers, skipping blanks, etc.  In that context string//1 is IMHO
a fair name.  This doesn't exclude an equivalent predicate with
a different name that fits another domain.

> I really don't see what it _could_ do other than what it does.

You could swap the clauses to make it greedy ... Most likely a
bad idea :-)

	Cheers --- Jan