Enumerations

Enumeration is the data type that is used to define, for example, possible values of some concept. For example, traffic light colors take three values:

enum TrafficLight <red yellow green>;

The names of the values become known to Perl 6 and thus you may use them directly in a program, for example:

say red;

This code prints the name of the value:

red

In this example, the actual values of the red, yellow, and green names are not important for us but Perl 6 assigns increasing integer values to them.

say red + yellow + green; # 6

This program is equivalent to say 0 + 1 + 2.

When the values are important, then you can specify them explicitly, as we do in the next example:

enum Floors (
    garage => -1, ground-floor => 0,
    first  => 1,  second       => 2);

We will see one of the examples of the enumeration in the definition of the Boolean type in Perl 6 in the next section.