Operators
Just as a sentence means nothing without a verb, anything you write in RuLa means nothing without operators. They make it possible for a variable to be defined, for a condition to work and for a rule to make sense.
The table below lists all available operators in alphabetical order, with a brief description. For a more extensive description of each individual operator, plus examples, click on it or visit the sub-pages in the menu on the left.

Available Operators and Keywords

Operator
Category
Description
=
Boolean
Compares. Evaluates to either true or false, delivering different outcomes.
!=
Boolean
Compares, true for 'is not equal to'.
>
Boolean
Compares, true for 'greater than'.
>=
Boolean
Compares, true for 'equal to or greater than'.
<
Boolean
Compares, true for 'less than'.
<=
Boolean
Compares, true for 'equal to or less than'.
:=
Special
Assignment, which can have any kind of expression on the right side of the operator.
+, -, /, *, %
Perform basic mathematical calculations.
[ , ]
List
Creates a new list from single values, allowing other list operators to perform actions on the new list.
ADD_YEARS
Date
Takes a date and adds a specified number of years to it.
AFTER
Date
Takes two dates, and checks if the first one comes after the second one.
Date
Takes two dates, and checks if the first one comes after, or is the same as, the second one.
ALL
List
Evaluates if all values in a list are true.
and
Boolean
Sets as condition that both expressions have to be true to have the entire expression evaluate to 'true'.
and then
Boolean
Similar as above, but when using 'and then', the second question is only asked when the first evaluates to 'true'.
AVG
Calculates the average value.
Known
Calculates the average of available values.
BEFORE
Date
Takes two dates, and checks if the first one comes before the second one.
Date
Takes two dates, and checks if the first one comes before, or is the same as, the second one.