//[[Documentation]] *Modules 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. **Name Space 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. // Currently, we have no means to prevent a programmer from writing arbitrary qualified names, and we have no means to abbreviate the module name part of 'exported' names. **Compile-Time Module Loading 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'''. ***Example { 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) } **Link-Time Module Loading ***SLIM 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. ***LMNtal Java 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. **System rulesets 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. //-There are three kinds of system rulesets: //++Built-in system rulesets that cannot be modified by users // ---Proxies for trans-membrane links fall into this category. //---Currently, they are processed in InterpretedRuleset //even when the translator is used. //++Built-in system rulesets that are described in LMNtal and //be modified //---Arithmetics falls in this category, but the current implementation //handles arithetics much like i. //++LMNtal ?v???O??????????W???[???????????????isystem_ruleset?j //i. ? ii. ??ATranslator ?????R???p?C????? runtiem.GlobalSystemRuleset //?N???X????B //??? iii. ??Aruntime.SystemRulesets ?N???X?????????B