Identifiers

Syntax

<identifier> ::= /[A-Za-z]_?([A-Za-z0-9]_?)*/
               | /_([A-Za-z0-9]_?)+/

Semantics

• _ is not an identifier by itself.
• _ in the beginning indicates the symbol may not be used and it's alright.
• _ is not allowed consecutively to improve readability.
• _ could be used in the end to form keyword-like identifiers (e.g., for_, type_, extension_).