Editor Support

Wax integrates with editors in two ways. Visual Studio Code has a dedicated extension that bundles everything. Every other editor combines two pieces: the tree-sitter-wax grammar for syntax highlighting, and the built-in wax lsp language server (see CLI Reference) for everything else. The extension and the server run the same analysis as the wax toolchain, so the language features are the same across editors.

Features

Available in VS Code, and in any editor with a Language Server Protocol client through wax lsp:

• Diagnostics as you type: syntax errors, type errors, and lints.
• Hover types, and inlay hints showing the inferred type on each un-annotated let binding.
• Go to definition, go to type definition, find references, and document highlight.
• Rename (a punned struct field is expanded so the field is preserved).
• Completion: the names in scope, a struct value’s fields and a numeric / array / v128 / memory / table receiver’s methods after ., and an intrinsic namespace’s functions after ::.
• Signature help while typing a call.
• Document outline, folding ranges, selection ranges, and semantic tokens.
• Formatting.

WebAssembly text (.wat) gets the same features: formatting, diagnostics, the outline, hover types, go-to-definition, go-to-type-definition, find references, document highlight, rename, folding, selection ranges, signature help, semantic tokens (identifiers coloured by the kind of index they resolve to), completion (where an index is expected, the names of the space it wants — functions, globals, locals, types, labels — since the instruction fixes the kind), inlay hints (after a numeric index, the name of the definition it refers to, so (local.get 0) reads as (local.get 0 $x)), and inactive-branch dimming for (@if) conditional compilation. Syntax highlighting otherwise comes from the extension’s own grammar in VS Code and from tree-sitter-wax elsewhere.

Visual Studio Code

The Wax extension (source in editors/vscode/) covers both .wax and .wat files with the full feature set above, plus snippets and commands to preview the compiled WAT or decompiled Wax side by side. It runs the toolchain compiled to WebAssembly in-process, with no separate wax install, so it works the same in desktop and web VS Code (including vscode.dev).

Other editors

Any editor with a Language Server Protocol client gets the feature set above by launching wax lsp. The editor starts the server itself, so wax only needs to be on your PATH; pair it with the tree-sitter grammar for highlighting. Ready-to-use configurations, each with a README, live under editors/:

• Neovim: register the tree-sitter-wax parser (nvim-treesitter or the built-in loader) and point vim.lsp at wax lsp.

• Helix: add the grammar and a [language-server.wax] entry running wax lsp (a ready-to-paste languages.toml is included).

• Emacs: wax-ts-mode provides tree-sitter highlighting, indentation, and imenu, with Eglot driving wax lsp for the rest. Requires Emacs 29+ and can be installed directly from GitHub using use-package with package-vc:

  (use-package wax-ts-mode
    :vc (:url "https://github.com/ocsigen/wax"
         :branch "main"
         :rev :newest
         :lisp-dir "editors/emacs")
    :hook (wax-ts-mode . eglot-ensure))
  
  ;; Optional: completion popup as you type. Without it, Eglot still serves
  ;; completions through the built-in `completion-at-point' (C-M-i).
  (use-package corfu
    :ensure t
    :custom
    (corfu-auto t)
    (corfu-auto-prefix 1)  ; pop up after one character, not the default 3
    :hook (wax-ts-mode . corfu-mode))
  

The server’s flags and behaviour (document sync, position-encoding negotiation) are documented under wax lsp in the CLI reference.

AI coding agents

Coding assistants that support the SKILL.md agent-skill format (Claude Code, Antigravity, Copilot, Codex, …) can be taught Wax with the wax skill shipped in the repository. Wax has almost no presence in model training data, so the skill bundles the complete language reference as a single context-loadable file and instructs the agent to validate everything it writes with wax check. Install it with the skills CLI:

npx skills add ocsigen/wax

or copy skills/wax/ into the agent’s skills directory (for Claude Code, .claude/skills/).