enum

As in C, the first member of the enum has a value of zero and each successive value is incremented by one.

X::SomeEnum::One # => One

You can specify the value of a member:

The type of an enum member is Int32 by default, even if you specify a different type in a constant value:

lib X
  enum SomeEnum
    A = 1_u32
end
X::SomeEnum # => 1_i32

You can use an enum as a type in a parameter or struct or union members:

lib X
    One
    Two
  end