Ovid, in prolog, attributed variables is what you are looking for.
Attributed variables are unbound variables but with a set of conditions or attributes attached. When an attributed variable is unified with anything else, its attached attributes (that are effectively callback predicates) are called, and their success or failure determines also the success or failure of the unification.
Most free prolog implementations (SWI-Prolog, YAP, XSB ) support them (unfortunately Language::Prolog::Yaswi doesn't), and it should be too difficult to extend AI::Prolog to also do so.
Attributed variables are mostly used in prolog to implement constraint logic programing (CLP). A good introduction to CLP is available on Bratko's Prolog Programing for Artificial Intelligence.
Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
Read Where should I post X? if you're not absolutely sure you're posting in the right place.
Please read these before you post! —
Posts may use any of the Perl Monks Approved HTML tags:
Outside of code tags, you may need to use entities for some characters:
- a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
Link using PerlMonks shortcuts! What shortcuts can I use for linking?
See Writeup Formatting Tips and other pages linked from there for more info.
| & || & |
| < || < |
| > || > |
| [ || [ |
| ] || ] ||