term_expansion/2

Description

term_expansion(Term, Expansion)

Defines an expansion for a term. This predicate, when defined and within scope, is automatically called by the expand_term/2 method. When that is not the case, the expand_term/2 method only uses the default expansions. Use of this predicate by the expand_term/2 method may be restricted by changing its default public scope.

The term_expansion/2 predicate may return a list of terms. Returning an empty list effectively suppresses the term.

Term expansion may be also be applied when compiling source files by defining the object providing access to the term_expansion/2 clauses as a hook object. Clauses for the term_expansion/2 predicate defined within an object or a category are never used in the compilation of the object or the category itself. Moreover, in this context, terms wrapped using the {}/1 compiler bypass control construct are not expanded and any expanded term wrapped in this control construct will not be further expanded.

Objects and categories implementing this predicate should declare that they implement the expanding protocol if no ancestor already declares it. This protocol implementation relation can be declared as either protected or private to restrict the scope of this predicate.

Modes and number of proofs

term_expansion(+nonvar, -nonvar) - zero_or_one
term_expansion(+nonvar, -list(nonvar)) - zero_or_one

Errors

(none)

Examples

term_expansion((:- license(default)), (:- license(gplv3))).
term_expansion(data(Millimeters), data(Meters)) :- Meters is Millimeters / 1000.