17. Globals

Valid global scope statements inclulde:

• Variable Declarations

• Struct Declarations

• Function and Procedure Declarations

• Function and Procedure Prototypes

• Typealias

All global statements are considered declarations. Global statements may occur in any order, given respective symbols are defined before being referenced.

18. Variable Declarations

In Gazprea values can be assigned to a global identifier. All globals must be immutable (const). If a global identifier is declared with the var specifier, then an error should be raised. This restriction is in place since mutable global variables would ruin functional purity. If functions have access to mutable global state then we can not guarantee their purity.

Globals must be initialized, but the initialization expressions may only contain a single _scalar_ literal. That means that functions and even previously defined globals may not appear on the RHS of a global declaration. The reason is because it is very difficult to evaluate variables and functions at compile time. Global expression evaluation could be deferred to runtime, but that has the disadvantage of changing errors from compile time to run time.