Lexical Structure

Tokens

After whitespace and comments are removed (see Source Files), the remaining input is a sequence of tokens.[sls.lex.tokens]

Identifiers

An identifier consists of one or more characters drawn from the following classes:[sls.lex.identifier.classes]

• The first character shall be a Unicode alphanumeric character or U+005F (LOW LINE, _).
• Each subsequent character shall be a Unicode alphanumeric character, U+005F (LOW LINE, _), or U+002D (HYPHEN-MINUS, -).

A U+002D (-) shall not appear as the first character of an identifier.[sls.lex.identifier.no-leading-hyphen]

Identifier Normalization

Two identifiers are considered the same if and only if their normalized forms are equal. The normalized form of an identifier is obtained by applying the following replacements in order over the characters of the source identifier:[sls.lex.identifier.normalization]

• The first character, if it is U+005F (_) or U+002D (-), is replaced with U+005F (_).
• Each subsequent U+005F (_) is replaced with U+002D (-).
• All other characters are left unchanged.

For example, foo_bar and foo-bar are the same identifier; _foo_bar and -foo-bar are the same identifier.[sls.lex.identifier.normalization-example]

The kebab-case form (with U+002D) is the canonical written form.[sls.lex.identifier.canonical-form]

Contextual Keywords

Slint has no globally reserved words. Each language construct is introduced by a contextual keyword: an identifier that has a special meaning only when it appears in a position where the grammar expects that construct.[sls.lex.contextual-keywords]