Editing Procedural programming (section)

=== Logic programming ===

In [[logic programming]], a program is a set of premises, and computation is performed by attempting to prove candidate theorems. From this point of view, logic programs are [[Declarative programming|declarative]], focusing on what the problem is, rather than on how to solve it.

However, the [[backward reasoning]] technique, implemented by [[SLD resolution]], used to solve problems in logic programming languages such as [[Prolog]], treats programs as goal-reduction procedures. Thus  clauses of the form:

:{{mono|1=H :- B<sub>1</sub>, …, B<sub>n</sub>.}}

have a dual interpretation, both as procedures

:to show/solve {{mono|1=H}}, show/solve {{mono|1=B<sub>1</sub>}} and … and {{mono|1=B<sub>n</sub>}}

and as logical implications:

:{{mono|1=B<sub>1</sub> and … and B<sub>n</sub> implies H}}.

A skilled logic programmer uses the procedural interpretation to write programs that are effective and efficient, and uses the declarative interpretation to help ensure that programs are correct.