For now, this reference is a best-effort document. We strive for validity and completeness, but are not yet there. In the future, the docs and lang teams will work together to figure out how best to do this. Until then, this is a best-effort attempt. If you find something wrong or missing, file an issue or send in a pull request.

Identifiers

Lexer:
IDENTIFIER :
      XID_start XID_continue*
   | _ XID_continue+

An identifier is any nonempty Unicode1 string of the following form:

Either

Or

  • The first character is _
  • The identifier is more than one character, _ alone is not an identifier
  • The remaining characters have property XID_continue

that does not occur in the set of keywords.

Note: XID_start and XID_continue as character properties cover the character ranges used to form the more familiar C and Java language-family identifiers.

1

Non-ASCII characters in identifiers are currently feature gated. This is expected to improve soon.