Execution of an expression is also called evaluation . 20 Generic unit. That is, the declaration of a generic unit represents a contract between the body of the generic and instances of the generic. Generic units can be used to perform the role that macros sometimes play in other languages. 21 Integer type.
Integer types comprise the signed integer types and the modular types.
A signed integer type has a base range that includes both positive and negative numbers, and has operations that may raise an exception when the result is outside the base range. 22 Library unit. A library unit is a separately compiled program unit, and is always a package, subprogram, or generic unit. A root library unit, together with its children and grandchildren and so on, form a subsystem . 23 Limited type.