up previous next
boolean operators
not E
E and F
E or F
where E and F are of type BOOL.
|
These operators have their usual meanings. Note that when two or more
boolean expressions are combined with AND, they are evaluated one by
one until a False expression is found. The rest are not evaluated.
For example, given the expression
A and B
, the system does not
attempt to evaluate B unless A evaluates to True. Similarly,
evaluation of a sequence of boolean expressions connected by OR stops
as soon as a True expression is found.