PRISM supports the use of constants, as seen in Example 2.
Constants can be integers, doubles or Booleans
and can be defined using literal values or as constant expressions (including in terms of each other) using the
keyword. For example:
The identifiers used for their names are subject to the same rules as variables.
Constants can be used anywhere that a constant value would be expected,
such as the lower or upper range of a variable (e.g.
N in Example 2),
the probability or rate associated with an update (
mu in Example 2),
or anywhere in a guard or update.
As will be described later constants can also be left undefined
and specified later, either to a single value or a range of values, using experiments.
Note: For the sake of backward-compatibility, the notation used in earlier versions of PRISM
const int and
const double) is still supported.