Emacs major mode for LUMOS - a type-safe schema language for Solana development.

✅ Syntax Highlighting - Keywords, types, attributes, comments ✅ Smart Indentation - Context-aware auto-indent ✅ LSP Integration - Auto-completion, diagnostics, hover, go-to-definition via lumos-lsp ✅ Comment Support - Line (//) and block (/* */) comments ✅ File Association - Automatic detection of .lumos files

1. Emacs 26.1+ - M-x version to check
2. lumos-lsp server - LSP features require the LUMOS Language Server:

cargo install lumos-lsp

3. lsp-mode - For LSP integration (optional but recommended):

(use-package lsp-mode :ensure t)

(use-package lumos-mode :ensure t :hook (lumos-mode . lsp-deferred))

(use-package lumos-mode :straight (lumos-mode :type git :host github :repo "getlumos/lumos-mode") :hook (lumos-mode . lsp-deferred))

1. Clone this repository:

git clone https://github.com/getlumos/lumos-mode.git ~/.emacs.d/lisp/lumos-mode

2. Add to your Emacs config:

;; Add to load path (add-to-list 'load-path "~/.emacs.d/lisp/lumos-mode") ;; Load mode (require 'lumos-mode) ;; Enable LSP (optional) (add-hook 'lumos-mode-hook #'lsp-deferred)

Open any .lumos file and lumos-mode will activate automatically:

;; Open a LUMOS file M-x find-file RET schema.lumos RET

lumos-mode automatically highlights:

• Keywords: struct, enum
• Types: u64, PublicKey, Vec, Option, etc.
• Attributes: #[solana], #[account], #[version], #[deprecated]
• Comments: // and /* */
• Field names: Identifiers before colons
• String literals: Text in quotes

With lsp-mode and lumos-lsp installed, you get:

Type and press M-TAB (or configure company-mode for automatic suggestions):

struct Player { wal<cursor> ← Press M-TAB to see completions } 

Syntax errors appear inline with flycheck:

struct Player { wallet: UnknownType ← Error: Undefined type 'UnknownType' } 

Press M-x lsp-describe-thing-at-point or hover over a symbol:

PublicKey ← Hover shows: "Solana PublicKey (32 bytes)" 

Press M-. to jump to definition:

player: Player ← M-. jumps to 'struct Player' definition 

Press M-? to find all references to a symbol.

Press M-x lsp-rename to rename a symbol across all files.

Press M-x lsp-execute-code-action to see available code actions.

lumos-mode provides smart indentation:

;; Auto-indent on newline struct Player { wallet: PublicKey, ← Press RET, cursor auto-indents } ;; Manual indent M-x indent-region ← Indent selected region

Customize indent width:

(setq lumos-indent-offset 4) ; Default: 2

Select a region and press M-; to comment/uncomment:

struct Player {} ← Select and M-; → // struct Player {} 

Type // for line comments or /* */ for block comments:

// This is a line comment /* * This is a block comment */ 

(use-package lumos-mode :ensure t :custom ;; Customize LSP server command (lumos-lsp-server-command '("lumos-lsp" "--log-level" "debug")) ;; Customize indentation (lumos-indent-offset 4) :hook ;; Enable LSP ((lumos-mode . lsp-deferred) ;; Enable auto-completion (lumos-mode . company-mode) ;; Enable syntax checking (lumos-mode . flycheck-mode)) :config ;; Custom keybindings (define-key lumos-mode-map (kbd "C-c C-c") 'lsp-execute-code-action) (define-key lumos-mode-map (kbd "C-c C-r") 'lsp-rename) (define-key lumos-mode-map (kbd "C-c C-f") 'lsp-format-buffer))

;; LSP server command (setq lumos-lsp-server-command '("lumos-lsp")) ;; Indentation width (setq lumos-indent-offset 2)

Create a file example.lumos:

#[solana] #[account] struct PlayerAccount { wallet: PublicKey, level: u16, experience: u64, inventory: Vec<Item>, } #[solana] struct Item { id: u32, name: String, quantity: u16, } #[solana] enum GameState { Lobby, Playing { round: u32 }, Finished, }

Open in Emacs:

emacs example.lumos

You'll get syntax highlighting, auto-completion, and diagnostics automatically!

Problem: No auto-completion or diagnostics.

Solution:

1. Check lumos-lsp is installed:

   which lumos-lsp

2. Check LSP is running:

   M-x lsp-describe-session

3. View LSP logs:

   M-x lsp-workspace-show-log

4. Restart LSP:

   M-x lsp-workspace-restart

Problem: No colors in .lumos files.

Solution:

1. Check mode is active:

   M-: major-mode RET ; Should show 'lumos-mode'

2. Force font-lock refresh:

   M-x font-lock-fontify-buffer

Problem: Wrong indentation levels.

Solution:

1. Check indent offset:

   M-: lumos-indent-offset RET ; Should show 2 (default)

2. Manually indent region:

   C-x h ; Select all M-x indent-region ; Re-indent

Problem: .lumos file opens in fundamental-mode.

Solution:

1. Check file association:

   M-: (assoc "\\.lumos\\'" auto-mode-alist) RET

2. Manually activate:

   M-x lumos-mode

3. Reload config and restart Emacs.

We have three levels of testing to ensure production quality:

Test individual components (syntax highlighting, indentation, comments, etc.)

# Quick test make test # Or manually emacs -batch -l lumos-mode.el -l lumos-mode-test.el -f ert-run-tests-batch-and-exit

Coverage:

• Mode loading and derivation
• File association (.lumos → lumos-mode)
• Syntax highlighting (keywords, types, attributes, comments)
• Indentation (structs, enums, nested blocks)
• Comment functionality (line and block)
• Custom variables

Test Emacs compatibility and package integration:

./test-integration.sh

Tests:

• ✓ Emacs version compatibility (26.1+)
• ✓ Unit test suite execution
• ✓ Byte compilation
• ✓ lumos-lsp server detection
• ✓ Mode loading in Emacs
• ✓ File association automation
• ✓ Syntax highlighting rules
• ✓ Indentation function
• ✓ Custom variables
• ✓ Package-lint validation

Test real user workflows:

./test-e2e.sh

Simulates:

• User installation via straight.el
• Opening .lumos files
• Syntax highlighting in action
• Indentation behavior
• Comment insertion
• Custom variable configuration
• LSP integration (if lumos-lsp available)

Before MELPA submission or major changes:

./test-all.sh

This runs all three test suites and reports overall status.

GitHub Actions automatically runs all tests on every push:

• Emacs Versions: 27.2, 28.2, 29.1, snapshot
• Checks: Tests, byte compilation, package-lint
• Status: See Actions tab

# Compile to bytecode make compile # Clean compiled files make clean

Contributions welcome! Please:

1. Fork the repository
2. Create a feature branch
3. Run tests: make test
4. Submit a pull request

• lumos - Core compiler and CLI
• vscode-lumos - VS Code extension
• intellij-lumos - IntelliJ IDEA plugin
• nvim-lumos - Neovim plugin
• tree-sitter-lumos - Tree-sitter grammar
• awesome-lumos - Examples and templates

• Website: lumos-lang.org
• Documentation: docs
• GitHub: getlumos
• Examples: awesome-lumos

Dual-licensed under MIT and Apache 2.0.