Skip to main content
Version: 5.x

IS, AS operators

IS, AS operators create an action that implements classification.


expression IS className
expression AS className


The IS operator creates an action which returns TRUE if the value of the expression belongs to the specified class.

The AS operator creates a property which returns the expression value if this value belongs to the specified class.


  • expression

    An expression which value is checked for belonging to the class.

  • className

    Class name. Class ID.


asOrder(object) = object AS Order;

person = DATA Human (Order);
isMale (Order o) = person(o) IS Male;