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A module is a set of rules packaged in a membrane with a module name definition:
| { module(modulename), RuleSet } |
The RuleSet is made available only when it is copied or 'loaded' outside the membrane. The module system of LMNtal provides a loading mechanism of modules.
A module can be defined either in the source file or in a separate file. In the latter case, the module can be either in source code or in intermediate code.
A single-level global name space is available for the names of atoms. An atom name p can be qualified with a module name m. The qualified atom name m.p can be referred to anywhere in the program.
When a program uses a qualified atom name of the form m.p, the membrane that contains the qualified atom name will be supplied with a copy of the rules specified in the module m.
{ module(acc).
acc.add(A), acc.value(N) :- acc.value(A+N).
acc.get(Res), acc.value(N) :- int(N) | Res=N, acc.value(N).
acc.new :- acc.value(0) }.
{ acc.new, acc.add(3), acc.add(4), acc.get(N) }
Modules defined in files in the $LMNTAL_HOME/installed/share/slim/lib directory or in the directories specified after the -I option of SLIM will be loaded, compiled (if not in the intermediate code) and linked before the exection of the user program starts.
Link-time module lookup is performed when the source file does not contain the definition of a referenced module. When a module m needs to be looked up, the file $LMNTAL_HOME/lib/src/m.lmn is loaded, compiled and linked before the execution of the user program starts, where $LMNTAL_HOME is the root directory of LMNtal.
A system ruleset is a set of global rules, namely rules applicable to every place in the membrane structure. For instance, built-in arithmetics (that evaluates x=1+2*3 to x=7, for example) is implemented as system rulesets.
A programmer can define his/her own system ruleset by defining the system_ruleset module.
