Topiary

Topiary is a universal code formatter that uses Tree-sitter grammars and queries to define formatting rules. Rather than implementing language-specific formatting logic, Topiary uses declarative Tree-sitter query files (.scm) to specify how code should be formatted.

When to Use This Skill

Activate this skill when:

• Formatting code in languages without dedicated formatters (JSON, TOML, Bash, Nickel, OCaml, OCamllex, CSS, OpenSCAD, SDML, WIT, or custom languages)
• Writing or debugging Tree-sitter query files (.scm)
• Configuring Topiary via languages.ncl for custom languages or indentation settings
• Setting up Topiary as part of a development workflow or CI/CD pipeline
• Learning Tree-sitter query syntax for code analysis

Key Concepts

Tree-Sitter Queries

Tree-sitter is a parser generator that creates language parsers from grammar definitions. Topiary uses Tree-sitter queries to analyze code structures and apply formatting rules. Queries match patterns in the syntax tree using S-expression syntax and decorate matched nodes with capture names (prefixed with @) that describe formatting actions.