Expands a term. The most common use is to expand a grammar rule into a clause. Users may override the default Logtalk grammar rule translator by defining clauses for the term_expansion/2 hook predicate.
The expansion works as follows: if the first argument is a variable,
then it is unified with the second argument; if the first argument is
not a variable and there are local or inherited clauses for the
term_expansion/2 hook predicate within scope, then this predicate is
called to provide an expansion that is then unified with the second
argument; if the
term_expansion/2 predicate is not used and the
first argument is a compound term with functor
-->/2 then the
default Logtalk grammar rule translator is used, with the resulting
clause being unified with the second argument; when the translator is
not used, the two arguments are unified. The
may return a single term or a list of terms.
This built-in method may be used to expand a grammar rule into a clause for use with the built-in database methods.
Automatic term expansion is only performed at compile time (to expand terms read from a source file) when using a hook object. This predicate can be used by the user to manually perform term expansion at runtime (for example, to convert a grammar rule into a clause).
Modes and number of proofs¶
expand_term(?term, ?term) - one