AbleScript

Expressions vs Statements

AbleScript strictly differentiates expressions and statements. Expressions cannot cause any side effects, they have value (can be used as part of expression) and they are only mathematical and logical operations or values.

On the other hand, statements cause side effects and they do not have any value. AbleScript's Abstact Syntax Tree consists only from statements and expressions are used only as parts of statements. For example control structures, definitions and function calls are statements.

For example

abc dim something() + 128;

is invalid, because functio call is a statement.

a + 3;

This is invalid too as expressions aren't valid AST members.