Appendix C — Tooling for HULK

While the core of HULK is its compiler and runtime, a modern programming language also requires a robust set of tools to support developers. This appendix outlines the high-level design of the HULK tooling ecosystem, focusing on editor integration and language support.

C.1 Editor Support and Syntax Highlighting

Syntax highlighting is the first step toward a good developer experience. For HULK, this is achieved through TextMate grammars and custom XML definitions.

C.1.1 TextMate Grammars

HULK’s syntax is primarily defined in vscode/syntaxes/hulk.tmLanguage.json. This JSON file uses regular expressions to categorize language constructs: - Keywords: Control flow (if, else, while, for), declarations (function, type, let, protocol, def). - Literals: Numbers, strings, and booleans. - Operators: Arithmetic, boolean, assignment (:=), and special macro operators (@, $).

To support HULK code blocks in Markdown and Quarto files, a specialized grammar hulk-markdown.tmLanguage.json is used to inject HULK highlighting into fenced code blocks.

C.1.2 Quarto Integration

For the static rendering of this book, Quarto uses a custom XML syntax definition (syntax/hulk.xml) that mirrors the rules of the TextMate grammar. This allows code blocks marked with ```hulk to be highlighted in the generated HTML and PDF formats.

C.2 Language Server Protocol (LSP)

The Language Server Protocol provides a standard way for editors to communicate with language-specific backends. A HULK LSP would ideally provide the following features:

C.2.1 Diagnostics

As the developer types, the HULK compiler should run in the background to report syntax errors and type mismatches. These appear as real-time feedback (e.g., red squiggly lines) in the editor.

C.2.2 Navigation and Go to Definition

By traversing the symbol table created during the semantic analysis phase, the LSP can provide “Go to Definition” for functions, variables, and types, allowing for easier navigation of large codebases.

C.2.3 Hover Information

Hovering over an identifier can show its inferred type or documentation. Since HULK features advanced type inference, the LSP reveals the exact type the compiler has deduced for a given variable.

C.3 VS Code Extension Development

The HULK VS Code extension (located in the vscode/ directory) serves as the primary integration point. Its main components are:

1. package.json Contributions: Defines the hulk language ID, associated file extensions (.hulk), and pointers to grammars and snippets.
2. Language Configuration: Specifies comment symbols (//), bracket pairs, and indentation rules.
3. Snippets: Pre-defined templates for common HULK constructs like function, type, and let (located in vscode/snippets/hulk.code-snippets).
4. LSP Client (Future Work): A TypeScript component that launches the HULK compiler in “LSP Mode” and manages communication between the editor and the compiler.

By following this architecture, HULK becomes not just a didactic language, but a well-integrated development environment.