Re: Extended DCG?

My example was boring. I thought I'd share this:

untextspeak(In, Out) :- trans( (In,Out), ([],[])).

trans --> [].
trans --> next, trans.

next --> \<"bang", !, \>"!".
next --> \<"c",        !,  \>"see ".
next --> \<"u",        !, \>"you ".
next --> \<"r",        !, \>"are ".
next --> \<"l8r",     !,  \>"later".
next --> \< (eyes,break(mouth),mouth), !. % ignore smileys. they are stupid.
next --> \< [X], \>[X]. % anything else gets through.

eyes --> ";"; ":".
break(P) --> []; \+P, [_], break(P).
mouth --> ")"; "("; "P".

test :- untextspeak("cu:-)l8rbang:--P",L),
           format(L).

If anyone has a better DCG for smileys, please feel free to contribute.
Now I will do something useful.

Samer.

On 12 Feb 2014, at 20:38, Alan Baljeu <[email protected]>
 wrote:

> I never bother with phrase/3, and just invoke my predicate xy(Rag, List, []).  So maybe I could do xy(Rag, (List1, List2), ([],[])) and design xy to work?  It's not clear to me how to pull this all together.
>  
> Alan Baljeu
> From: "Abdallah, Samer" <[email protected]>
> To: Alan Baljeu <[email protected]> 
> Cc: Prolog <[email protected]> 
> Sent: Wednesday, February 12, 2014 1:48:07 PM
> Subject: Re: [SWIPL] Extended DCG?
> 
> Hi all,
> I would just like to use this opportunity to request again that phrase/3 be 
> allowed to work with arbitrary types in the last two positions, not just
> lists, or an alternative, say gphrase/3  (for generalised phrase), or
> rundcg/3 which works exactly like phrase/3 but allows arbitrary types.
> Or even better, put phrase/3 back how it was and introduce a type
> checking list_phrase/3 or safe_phrase/3 for people who want that.
> 
> It used to be the case that an extended DCG for writing a transducer
> as  Alan would like, was easy to write using ordinary DCG notation.
> The type of the threaded argument would be a pair of lists (L,R)
> instead of just one list. In my DCG library I have some DCG rules for
> working with this conveniently. For example, operators (\<)//1 and (\>)//1 
> apply a DCG phrase to the left or right member of the pair:
> 
> :- op(800, \<, fy).
> :- op(800, \>, fy).
> 
> \<(P, (L1,R), (L2,R)) :- phrase(P,L1,L2). 
> \>(P, (L,R1), (L,R2)) :- phrase(P,R1,R2)
> 
> Then you can do things like \< integer(X) to read an integer from
> from the left sequence and \> [int(X)] to write a term to the right, and so on.
> Alan's scenario is easily and efficiently dealt with.
> 
> Forcing us to use lists for the arguments to phrase/3 forces an ugly
> encoding of the pair in a singleton list, e.g. as [(L,R)], and, if the list
> is [X] and we already have a bunch of predicates that want to work
> on X,  forces an unnecessary layer of meta-predicates to get through 
> the wrapping.
> 
> For the moment, I have deleted the two offending lines from boot/dcg.pl
> in my local installations, but of course, this is not good for the portability
> of my code!
> 
> cheers,
> Samer
> 
> 
> (
> 
> On 11 Feb 2014, at 16:51, Alan Baljeu <[email protected]>
> wrote:
> > I have a scenario where I'm mapping a list to a second list, but it's not 1 to 1.  For this, it would be nice to use an extended DCG, that supports two independent lists.  Does such a thing exist?
> >  
> > Alan Baljeu
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> 
> 

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