# Syntax Highlighting

This document describes the currently implemented Masterbelt syntax highlighting captures.

Highlighting covers every keyword and the language's declarations, bindings, match patterns, type expressions, operators, literals, and comments. Future captures must extend this document before or together with query changes.

## Captures

Keywords:

- `visibility_modifier` is captured as `@keyword`.
- The `const` keyword is captured as `@keyword`.
- The `type` keyword is captured as `@keyword`.
- The `use` keyword is captured as `@keyword`.
- The `from` keyword is captured as `@keyword`.
- The `as` keyword is captured as `@keyword`.
- `field_modifier` (`readonly`, `writable`, `primary`) is captured as `@keyword.modifier`.
- `effect_modifier` (`asyncable`, `failable`, `cancellable`) is captured as `@keyword.modifier`.
- The `fn` keyword is captured as `@keyword`.
- The `enum` keyword is captured as `@keyword`.
- The `return` keyword is captured as `@keyword`.
- The `master`, `record`, and `source` keywords are captured as `@keyword`.
- The `filter`, `include`, and `exclude` keywords are captured as `@keyword`.
- The `validation`, `each`, `all`, `validate`, and `assert` keywords are captured as `@keyword`.
- The `static` and `select` keywords are captured as `@keyword`.
- The `scope` context keyword is captured as `@keyword`; the `indexed` context keyword is captured as `@keyword.modifier`.
- The `if`, `else`, `match`, `for`, `in`, `let`, and `fail` keywords are captured as `@keyword`, as are the `break` and `continue` statements.

Definitions and identifiers:

- Const item names are captured as `@constant`.
- Type declaration names are captured as `@type.definition`.
- Type parameter names on a generic type declaration are captured as `@type.parameter`.
- Product type field names are captured as `@property`.
- Product literal field names are captured as `@property`.
- The type prefix of a typed product literal is captured as `@type`.
- Function type parameter names are captured as `@variable.parameter`.
- Enum declaration names are captured as `@type.definition`.
- Enum variant names are captured as `@constant`.
- In a member access expression `Target.Member`, the target identifier is captured as `@type` and the member identifier is captured as `@constant`.
- Top-level function declaration names are captured as `@function`.
- Method names declared inside a product type are captured as `@function.method`.
- Master declaration names are captured as `@type.definition`.
- The `validate` rule name of a master validation rule is captured as `@function`.
- The scope name of a master scope declaration is captured as `@function`.
- The projection name of a master select section is captured as `@type.definition`.
- The source-kind identifier of a master source entry is captured as `@type`.
- Master source option names are captured as `@property`.
- Local `const` binding names are captured as `@constant`; `let` binding names, assignment targets, and `for` loop binding names are captured as `@variable`.

Match patterns:

- An enum pattern `Target.Variant` captures the target identifier as `@type` and the variant identifier as `@constant`.
- A product pattern's type identifier is captured as `@type`, its field names as `@property`, and its `as` binding as `@variable`.
- A type pattern's `as` binding is captured as `@variable`.
- The wildcard pattern `_` is captured as `@variable.builtin`.

Operators:

- A unary or binary expression's operator token is captured as `@operator`. The capture uses the expression's `operator` field, so the `<` `>` of a generic type application and the `|` of a union type — which are the same tokens in type position — are not coloured as operators.
- The `=>` arrow token and the variadic `*` prefix are captured as `@operator`.

Type expressions:

- `named_type` is captured as `@type`.
- `reserved_type_identifier` is captured as `@type.builtin`.
- The constructor identifier of `generic_type` is captured as `@type`.

Literals and comments:

- `null_literal` is captured as `@constant.builtin`.
- `bool_literal` is captured as `@boolean`.
- `integer_literal` is captured as `@number`.
- `string_literal` is captured as `@string`.
- `line_comment` is captured as `@comment`.
- `block_comment` is captured as `@comment`.
- `doc_comment` is captured as `@comment.documentation`.