A.6.2.1 any, findall and findallset

KnowledgeWorks and Prolog User Guide > A Common Prolog > A.6 Calling Prolog From Lisp > A.6.2 Interface Functions

A.6.2.1 any, findall and findallset

Three simple interface functions call logic . They are any , findall , and findallset . Each takes two arguments: a result expression to instantiate and a goal expression. any returns the first solution found. findall returns all solutions. findallset returns all solutions deleting duplicates.

Assuming the definitions for fact and color from the previous examples.


|(any '(?x is the factorial of 5) '(fact 5 ?x))

returns:

|(120 IS THE FACTORIAL OF 5)


|(findall '(?x is a color) '(color ?x))

returns:

|((RED IS A COLOR) (BLUE IS A COLOR)

  (GREEN IS A COLOR))


|(findall '?y '(or (= ?y 5) (= ?y 5)))

returns:

|(5 5)

|(findallset '?y '(or (= ?y 5) (= ?y 5)))

returns:

|(5)

findall and findallset will hang if a goal expression generates an infinite solution set.

More powerful all solution predicates (bagof and setof ) are available from within Common Prolog.

KnowledgeWorks and Prolog User Guide (Unix version) - 22 Dec 2009