built-in method
setof/3
Description
setof(Template, Goal, List)
Collects a set of solutions for the goal for each set of instantiations
of the free variables in the goal. The solutions are sorted using
standard term order. The free variables in the goal are the variables
that occur in the goal but not in the template. Free variables can be
ignored, however, by using the ^/2
existential qualifier. For
example, if T
is term containing all the free variables that we want
to ignore, we can write T^Goal
. Note that the term T
can be
written as V1^V2^...
.
When there are free variables, this method is re-executable on backtracking. This method fails when there are no solutions, never returning an empty list.
This built-in meta-predicate is declared as a private method and thus cannot be used as a message to an object.
Meta-predicate template
setof(*, ^, *)
Modes and number of proofs
setof(@term, +callable, -list) - zero_or_more
Errors
Goal
is a variable:instantiation_error
Goal
is neither a variable nor a callable term:type_error(callable, Goal)
Goal
is a call to a non-existing predicate:existence_error(procedure, Predicate)
Examples
setof(Template, Goal, List)
setof(Template, ::Message, List)
setof(Template, Object::Message, List)