(module)/1 current_module/1 is_module/1 - checks/generates an existing module-name module_call/2, ':'/2 - calls a predicate hidden in a module module_name/3 - adds the name of a module to a symbol module_predicate/3 - adds the name of a module to a goal modules/1 - gives the list of existing modules
The following example:
:-module m1. :-public d/1. a(1). a(2). a(3). a(4). d(X):-a(X). :-module m2. :-public b/1. b(X):-c(X). c(2). c(3). c(4). c(5). c(6). :-module m3. :-public test/1. test(X):-b(X),d(X). :-module user. go:-modules(Ms),write(Ms),nl,fail. go:-test(X),write(X),nl,fail.
Executiong ?-go. will generate the following output:
[user/0,m1/0,m2/0,m3/0] 2 3 4
Starting with version 3.30, predicates in the BinProlog system
itself which are not intended to be used by applications, are hidden in
the module prolog but can be accessed by calling them with
'prolog:my_predicate'(...).
Explicit naming of the module where the hidden predicate is defined should be used when call/1, findall/3 etc. uses a hidden predicate, even if it is in the module itself.
This draconian constraint is motivated by simplicity of
BinProlog's stateless purely source-level module system.
Basically predicates in a module have their names prefixed
as in 'my_current_module:my_predicate' in a preprocessing step, except if they are declared \verbpublic or are known to
the system as being so (i.e. in the case of builtins).
This basic concept of modules (essentially the same as
what can be achieved with extern and static
declarations in C) covers only compiled code,
and is mostly intended to ensure
multiple name spaces with a very simple semantics
and no aditional space or time overhead. On the other
hand use of linear and intutionistic implication
is suggested for dynamic modular and hypothetical reasoning
constructs.
Meta-predicate declarations are not supported at this time (mostly
because they are at least as cumbersome as just puting the right
name extension in argument positions which require it :-)), but they
might be added in the future if a significant number of
users will ask to have them.
Note that builtins and predicates defined in a special module user
are always public. A public predicate keeps its name unchanged
in the global name space while hidden predicates have their
names prefixed by the name of the module in their
definitions and in all their statically obvious (first-order)
uses.
Alternatively, module/2 allows to define a module and its public predicates with one declaration as in:
:-module(beings,[cat/4,dog/4,chicken/2,fish/0,maple/1,octopus/255]).