Sema for Vim

Sema support for Vim — a Lisp with first-class LLM primitives.

Vim and Neovim support for Sema: syntax highlighting, filetype detection, and Lisp-aware editor settings for .sema files.

Install

Because this repository uses the standard plugin layout (ftdetect/, ftplugin/, syntax/ at the root), no runtimepath override is needed — install it like any other plugin.

vim-plug

Plug 'sema-lisp/sema.vim'

lazy.nvim

{ "sema-lisp/sema.vim" }

packer.nvim

use "sema-lisp/sema.vim"

Native packages (:packadd / Vim 8+ & Neovim)

git clone https://github.com/sema-lisp/sema.vim.git \
  ~/.vim/pack/plugins/start/sema.vim
# Neovim:
git clone https://github.com/sema-lisp/sema.vim.git \
  ~/.local/share/nvim/site/pack/plugins/start/sema.vim

Manual

Copy the directories into your Vim (~/.vim) or Neovim (~/.config/nvim) config:

git clone https://github.com/sema-lisp/sema.vim.git
cp -r sema.vim/{ftdetect,ftplugin,syntax} ~/.vim/

Features

• Filetype detection — .sema files are automatically detected as sema.
• Syntax highlighting — special forms, builtins (including LLM/agent primitives like llm/chat, agent/run, defagent, deftool), threading macros (->, ->>, as->), keyword literals, strings with escapes, numbers, booleans, character literals, quoting/unquoting, line (;) and block (#| … |#) comments, and definition-name highlighting.
• Lisp-aware editing — lisp mode with a curated lispwords list (including Sema forms such as defagent, deftool, with-budget), 2-space indentation, and iskeyword extended for Sema identifiers (!?/-<>*#).
• Comment settings — commentstring and comments configured for ; line comments.

This is a pure Vimscript plugin — no external dependencies, works in both Vim and Neovim.

Requirements

• Vim 7+ or Neovim — the plugin is pure Vimscript with no runtime dependencies.
• The sema binary is only needed to run Sema code, not for editing. Install it from the Sema project.

LSP Support (optional)

Sema ships a built-in language server (sema lsp) providing completions, hover docs, go-to-definition, find references, rename, signature help, diagnostics, document symbols, and code lens. This plugin does not start it for you — wire it up with your LSP client of choice.

nvim-lspconfig (Neovim built-in LSP)

vim.api.nvim_create_autocmd('FileType', {
  pattern = 'sema',
  callback = function()
    vim.lsp.start({
      name = 'sema',
      cmd = { 'sema', 'lsp' },
      root_dir = vim.fs.dirname(vim.fs.find({ 'sema.toml', '.git' }, { upward = true })[1]),
    })
  end,
})

coc.nvim

Add to :CocConfig:

{
  "languageserver": {
    "sema": {
      "command": "sema",
      "args": ["lsp"],
      "filetypes": ["sema"]
    }
  }
}

The Sema LSP server also emits a custom sema/evalResult notification for inline evaluation results; displaying it requires a custom client handler (see the Sema documentation).

Highlighting Groups

Group	What it covers
semaSpecial	Special forms (define, lambda, if, defagent…)
semaBuiltin	Builtin functions (map, llm/chat, file/read…)
semaThreading	Threading macros (->, ->>, as->)
semaOperator	Arithmetic/comparison operators (+, -, <=…)
semaKeyword	Keyword literals (:model, :temperature…)
semaString	String literals
semaStringEscape	Escape sequences in strings
semaNumber	Integer and float literals
semaBoolean	#t, #f, true, false
semaConstant	nil
semaCharacter	Character literals (#\a, #\space…)
semaComment	Line comments (;)
semaBlockComment	Block comments (#| … |#)
semaTodo	TODO/FIXME/XXX/HACK/NOTE in comments
semaDefineVar	Names bound by (define name …) / set!
semaDefineFun	Names bound by (define (f …)), defun, defmacro…
semaQuote	Quote (') and quasiquote (`) prefixes
semaUnquote	Unquote (,) and unquote-splicing (,@)
semaParens	Parentheses, brackets, and braces

Override any group in your colorscheme to customise appearance.

Links

• Website — sema-lang.com
• Playground — sema.run
• Documentation — sema-lang.com/docs
• Grammar — tree-sitter-sema
• Repository — sema-lisp/sema.vim

License

MIT © Helge Sverre