Prolog Language Terms with named fields using library(record)


Example

The [record][1] library provides the ability to create compound terms with named fields. The directive :- record/1 <spec> compiles to a collection of predicates that initialize, set and get fields in the term defined by <spec>.

For example, we can define a point data structure with named fields x and y:

:- use_module(library(record)).

:- record point(x:integer=0,
                y:integer=0).

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?- default_point(Point), point_x(Point, X), set_x_of_point(10, Point, Point1).
Point = point(0, 0),
X = 0,
Point1 = point(10, 0).

?- make_point([y(20)], Point). 
Point = point(0, 20).

?-  is_point(X). 
false.

?- is_point(point(_, _)).
false.

?- is_point(point(1, a)).
false.

?- is_point(point(1, 1)).
true.

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