2.1 Notation🔗ℹ

Like most languages, Rhombus syntax builds on a set of rules for parsing characters into tokens. Unlike most languages––but like Lisp, Scheme, and Racket—Rhombus syntax uses an additional layer of rules for grouping and nesting tokens. For languages in the Lisp family, the intermediate structure is S-expression notation, which gives Lisp its parenthesized, prefix notation. For Rhombus, the intermediate structure is shrubbery notation, which is designed to support traditional infix operators and rely on line breaks and indentation for grouping and nesting.

See Shrubbery Notation for complete details, but the basics (such as numbers and identifiers) look like many other languages, and here are a few extra hints:

• Shrubbery notation is whitespace-sensitive, so line breaks and indentation matter.

• The : and | tokens are not operators, but instead determine program structure along with line breaks and indentation. Multi-character tokens with : and | can be operators, such as ::, :~, or ||.

• Keywords start with ~, and they are a distinct syntactic category from identifiers and operators.

• Single-quote marks '…' are used for quoting code (i.e., shrubbery forms), not strings.

• Indentation rules still apply within (…), […], {…}, and '…'.