SWI-Prolog -- require/1

Availability:built-in

require(+ListOfNameAndArity)

Declare that this file/module requires the specified predicates to be defined ``with their commonly accepted definition''. This predicate originates from the Prolog portability layer for XPCE. It is intended to provide a portable mechanism for specifying that this module requires the specified predicates.

The implementation normally first verifies whether the predicate is already defined. If not, it will search the libraries and load the required library.

SWI-Prolog, having autoloading, does not load the library. Instead it creates a procedure header for the predicate if it does not exist. This will flag the predicate as `undefined'. See also check/0 and autoload/0.