What are the rules for identifiers in Typst?

xkevio · September 25, 2024, 12:11pm

According to the lexer inside of Typst’s source code, an identifier is valid if it follows the Unicode standard uax31 and, additionally, Typst allows _ as a starting and continuing character and - as a continuing character.

github.com

typst/typst/blob/main/crates/typst-syntax/src/lexer.rs#L898-L911


      
          /// Whether a string is a valid Typst identifier.
          ///
          /// In addition to what is specified in the [Unicode Standard][uax31], we allow:
          /// - `_` as a starting character,
          /// - `_` and `-` as continuing characters.
          ///
          /// [uax31]: http://www.unicode.org/reports/tr31/
          #[inline]
          pub fn is_ident(string: &str) -> bool {
              let mut chars = string.chars();
              chars
                  .next()
                  .is_some_and(|c| is_id_start(c) && chars.all(is_id_continue))
          }

As for how users should name their variables and functions, the standard seems to be kebab-case. Referencing a variable with just an underscore won’t work since that is probably reserved for explicitly nameless variables.