SWI-Prolog contains two special modules. The first one is the module
system
. This module contains all built-in predicates
described in this manual. Module system
has no default
module assigned to it. The second special module is the module user
.
This module forms the initial working space of the user. Initially it is
empty. The default module of module user
is system
,
making all built-in predicate definitions available as defaults.
Built-in predicates thus can be overruled by defining them in module user
before they are used.
All other modules default to module user
. This implies
they can use all predicates imported into user
without
explicitly importing them.