test lisp-form
lisp-form
A single lisp form.
Succeeds if and only if the lisp-form returns a non-nil value. Any currently bound variables may be used in the lisp form.
(test (> ?c 10))
(test (not (and (eq ?a ?b) (member ?b ?c))))
KnowledgeWorks and Prolog User Guide (Unix version) - 26 Feb 2015