Tutorial: Rules

After having defined your nouns, verbs and statements, you can define the active elements of your app by writing rules. A rule consists of three parts:

  • When: the conditions under which the rule will execute.
  • Then: the actions that will be performed when the rule executes.
  • Do: the operations that are used in the when and/or then parts of the rule.

Since rules are the most elaborate aspect of writing apps in Hapsah, we have divided this topic into several tutorials explaining the following topics:


The entities, descriptors and constant values that take part in the when part of a rule.


The criteria that describe when a rule is to be triggered for execution.


The value manipulations that make out the do part of a rule in conditions and/or actions.


The actions that are performed when the rule executes and make out the then part of a rule.