Declarations of constants are introduced using the const keyword. A value is not necessarily assigned to a value. Three syntactic rules are allowed:

1 const const_id_1 = V;
2
3 const const_id_2 : Dom = V;
4
5 const const_id_3 : Dom;

The first case simply declares a constant const_id_1 with the value V where V is any constant expression. The type associated to const_id_1 is the type of V. The second case permits to declare the domain Dom of the constant const_2; this is mainly useful for integer variables. In the last case the value of const_id_3 is not given; since no type inference exists in AltaRica a domain must be specified.

The constant value V used to define a constant can refer to other constants. For instance, the following code defines an integer constant according to a Boolean flag:

1 const LARGE_MODEL : bool = true;
2
3 const SMALL_QUEUE_SIZE = 2;
4 const LARGE_QUEUE_SIZE = 20;
5
6 const QUEUE_SIZE = if LARGE_QUEUE then LARGE_QUEUE_SIZE else SMALL_QUEUE_SIZE;
7
8 domain Queue = bool[QUEUE_SIZE];

Compound constants are specified between braces {}:

• For arrays, values are simply the elements of the array separated by commas;
• For structures, a list of field assignments separated by commas is given. The field name is prefixed with a dot (.).

The following example defines a constant array and a constant structure:

1 const CST_ARRAY = { 1, 2 ,3 };
2 const CST_STRUCT = { .flag = true, .values = CST_ARRAY };