13.6 Variables

Variables denote values, and appear as constituents of expressions.

     typed_variable_declaration ::=
       <typed_variable_>simple_name : <typed_string_>name :=  string_expression ;
     
     variable_declaration ::=
       <variable_>simple_name := expression;

The elaboration of a variable declaration introduces the variable and assigns to it the value of the expression. The name of the variable is available after the assignment symbol.

A typed_variable can only be declare once.

a non-typed variable can be declared multiple times.

Before the completion of its first declaration, the value of variable is the null string.