Editor Support

Sema has editor plugins for VS Code, Vim/Neovim, Emacs, Helix, and Zed. All plugins provide syntax highlighting for the full standard library (350+ functions), special forms, keyword literals, character literals, strings, numbers, comments, and LLM primitives.

Source code for all editor plugins is in the editors/ directory.

VS Code

TextMate grammar-based extension with full syntax highlighting, bracket matching, auto-closing pairs, comment toggling, and indentation support.

Install

EXT_DIR=~/.vscode/extensions/helgesverre.sema-0.1.0
mkdir -p "$EXT_DIR/syntaxes"
BASE=https://raw.githubusercontent.com/HelgeSverre/sema/main/editors/vscode/sema
curl -fsSL "$BASE/package.json" -o "$EXT_DIR/package.json"
curl -fsSL "$BASE/language-configuration.json" -o "$EXT_DIR/language-configuration.json"
curl -fsSL "$BASE/syntaxes/sema.tmLanguage.json" -o "$EXT_DIR/syntaxes/sema.tmLanguage.json"
curl -fsSL "$BASE/icon.png" -o "$EXT_DIR/icon.png"

Restart VS Code after installing.

Features

• Syntax highlighting (special forms, builtins, LLM primitives, keywords, strings, numbers, booleans, character literals, comments)
• Bracket matching and auto-closing for (), [], {}, ""
• Comment toggling (Ctrl+/ / Cmd+/)
• Indentation rules for all bracket types
• Arithmetic/comparison operator highlighting

Vim / Neovim

Pure Vimscript plugin with syntax highlighting, filetype detection, and Lisp-aware indentation.

vim-plug

Plug 'helgesverre/sema', { 'rtp': 'editors/vim' }

lazy.nvim

{
  "helgesverre/sema",
  config = function(plugin)
    vim.opt.rtp:append(plugin.dir .. "/editors/vim")
  end,
}

Manual (Vim)

mkdir -p ~/.vim/syntax ~/.vim/ftdetect ~/.vim/ftplugin
BASE=https://raw.githubusercontent.com/HelgeSverre/sema/main/editors/vim
curl -fsSL "$BASE/syntax/sema.vim" -o ~/.vim/syntax/sema.vim
curl -fsSL "$BASE/ftdetect/sema.vim" -o ~/.vim/ftdetect/sema.vim
curl -fsSL "$BASE/ftplugin/sema.vim" -o ~/.vim/ftplugin/sema.vim

Manual (Neovim)

mkdir -p ~/.config/nvim/syntax ~/.config/nvim/ftdetect ~/.config/nvim/ftplugin
BASE=https://raw.githubusercontent.com/HelgeSverre/sema/main/editors/vim
curl -fsSL "$BASE/syntax/sema.vim" -o ~/.config/nvim/syntax/sema.vim
curl -fsSL "$BASE/ftdetect/sema.vim" -o ~/.config/nvim/ftdetect/sema.vim
curl -fsSL "$BASE/ftplugin/sema.vim" -o ~/.config/nvim/ftplugin/sema.vim

Features

• Full syntax highlighting (special forms, 350+ builtins, LLM primitives, keywords, character literals, comments)
• Automatic filetype detection for .sema files
• Lisp-aware indentation with correct lispwords for all Sema special forms
• Comment string configured for ;

Emacs

Major mode derived from prog-mode with Lisp-aware indentation, REPL integration, and imenu support.

Manual

mkdir -p ~/.emacs.d/site-lisp
curl -fsSL https://raw.githubusercontent.com/HelgeSverre/sema/main/editors/emacs/sema-mode.el \
  -o ~/.emacs.d/site-lisp/sema-mode.el

(add-to-list 'load-path "~/.emacs.d/site-lisp")
(require 'sema-mode)

use-package

(use-package sema-mode
  :load-path "~/.emacs.d/site-lisp"
  :mode "\\.sema\\'")

Doom Emacs

In packages.el:

(package! sema-mode :recipe (:local-repo "~/.emacs.d/site-lisp"))

In config.el:

(use-package! sema-mode :mode "\\.sema\\'")

Features

• Syntax highlighting (special forms, builtins, keyword literals, booleans, character literals, numbers, strings, comments)
• Buffer-local Lisp indentation with Sema-specific form rules
• REPL integration — start a Sema REPL and send code interactively
• imenu support for navigating defun, define, defmacro, defagent, deftool, and define-record-type definitions
• Electric pairs for (), [], {}, ""
• Proper sexp navigation with quote ('), quasiquote (`), and unquote (,) prefix handling

Key Bindings

Key	Command	Description
C-c C-z	sema-repl	Start or switch to the Sema REPL
C-c C-e	sema-send-last-sexp	Send sexp before point to REPL
C-c C-r	sema-send-region	Send selected region to REPL
C-c C-b	sema-send-buffer	Send entire buffer to REPL
C-c C-l	sema-run-file	Run current file with sema

Configuration

;; Path to the sema binary (default: "sema")
(setq sema-program "/path/to/sema")

Helix

Syntax highlighting using the dedicated tree-sitter-sema grammar, with Sema-specific highlight queries, text objects, and indentation.

Install

1. Download and append the language config to your Helix configuration:

   BASE=https://raw.githubusercontent.com/HelgeSverre/sema/main/editors/helix
   curl -fsSL "$BASE/languages.toml" >> ~/.config/helix/languages.toml

   If you already have a languages.toml, manually merge the [[language]] and [[grammar]] sections.

2. Download the query files:

   mkdir -p ~/.config/helix/runtime/queries/sema
   for f in highlights indents textobjects injections; do
     curl -fsSL "$BASE/queries/sema/$f.scm" \
       -o ~/.config/helix/runtime/queries/sema/$f.scm
   done

3. Fetch and build the Sema grammar:

   hx --grammar fetch
   hx --grammar build

4. Verify:

   hx --health sema

Features

• Syntax highlighting via tree-sitter queries (special forms, builtins, LLM primitives, keywords, booleans, character literals, strings, comments)
• Text objects — maf/mif for function definitions, mac/mic for agent/tool definitions
• Smart auto-pairs for (), [], {}, ""
• Indentation support
• ; line comments

How It Works

The grammar = "sema" setting tells Helix to parse .sema files using the tree-sitter-sema grammar, which provides native support for Sema-specific syntax like keyword literals (:name), hash maps, and vectors. Custom query files in queries/sema/ provide Sema-specific captures for LLM primitives, slash-namespaced builtins (string/trim, llm/chat), and special forms like defagent and deftool.

Zed

Extension using the dedicated tree-sitter-sema grammar with full syntax highlighting, bracket matching, code outline, and auto-pairs.

Install

1. Open Zed
2. Go to Zed → Extensions (or Cmd+Shift+X)
3. Click Install Dev Extension
4. Select the editors/zed directory from the Sema repository

Features

• Syntax highlighting (special forms, 350+ builtins, LLM primitives, keyword literals, booleans, nil, strings, comments)
• Smart auto-pairs for (), [], {}, ""
• Code outline for define, defun, defmacro, defagent, deftool
• Bracket matching
• ; line comments
• 2-space indentation