tree-sitter-ilo

Tree-sitter grammar for the ilo programming language.

ilo is a token-optimised programming language for AI agents. Its dense prefix-and-sigil syntax is unusual, but its lexical structure is unambiguous, so this grammar gets every editor with tree-sitter support to colour ilo code correctly.

Status

Initial release. Covers every shape that appears in the upstream ilo/examples/ corpus (97% of 229 sample programs parse without ERROR nodes). The handful that don't are multi-line bodies with blank lines inside them, which the current scanner doesn't fully disambiguate from declaration boundaries; queued for the next release.

What this enables

• Neovim via nvim-treesitter once the grammar is added to its parsers list
• Helix via a [[grammar]] block pointing at this repo in languages.toml
• Zed via native tree-sitter discovery once published to npm
• VS Code via tree-sitter-based extensions, alongside the existing TextMate grammar
• GitHub pending Linguist PR; once accepted, .ilo files on github.com get syntax highlighting
• Any tree-sitter tool ast-grep, comby, anything that walks tree-sitter ASTs

Layout

grammar.js                  the grammar DSL
src/parser.c                generated parser (committed)
src/grammar.json            generated grammar metadata
src/node-types.json         generated node-types schema
src/scanner.c               external scanner (newline / decl-terminator handling)
queries/
  highlights.scm            syntax highlighting
  indents.scm               auto-indent rules
  injections.scm            nested language injections (regex)
  locals.scm                local-scope variable resolution
bindings/
  node/                     Node.js bindings for npm
  rust/                     Rust bindings for crates.io
test/corpus/                tree-sitter test fixtures
package.json                npm metadata
Cargo.toml                  crates.io metadata
binding.gyp                 node-gyp build config

Build

# generate parser from grammar.js
tree-sitter generate

# run corpus tests
tree-sitter test

# parse a file
tree-sitter parse path/to/file.ilo

You need tree-sitter CLI installed (npm install -g tree-sitter-cli or cargo install tree-sitter-cli).

Using from Neovim (local checkout)

In your Neovim config:

local parser_config = require("nvim-treesitter.parsers").get_parser_configs()
parser_config.ilo = {
  install_info = {
    url = "~/path/to/ilo-tree-sitter",
    files = { "src/parser.c", "src/scanner.c" },
    branch = "main",
  },
  filetype = "ilo",
}

Then :TSInstallFromGrammar ilo and the highlight queries in queries/ get picked up automatically when you open a .ilo buffer.

Using from Helix

In your languages.toml:

[[language]]
name = "ilo"
scope = "source.ilo"
file-types = ["ilo"]
roots = []
comment-token = "--"
indent = { tab-width = 2, unit = "  " }

[[grammar]]
name = "ilo"
source = { git = "https://github.com/ilo-lang/ilo-tree-sitter", rev = "main" }

Then hx --grammar fetch and hx --grammar build.

Grammar coverage

The grammar covers:

• Function declarations name args:type ...>return-type;body
• Type signatures primitive (n, t, b, _), parameterised (L T, O T, R T E, M K V, F A R), sum (S a b c), named records
• Prefix operators +a b, *x y, >=x 0, every arithmetic / comparison / boolean shape
• Control flow ?subj{...}, ?subj{...}{...} (ternary), ?{arms} (match), wh c{body}, @v xs{body} (foreach), @i a..b{body} (range), ret, brk, cnt
• Calls f a b, f! a b (auto-unwrap), f!! a b (panic-unwrap), f() (zero-arg)
• Pipes x>>f>>g
• Field access r.field, r.?optional, chained, on parenthesised expressions
• Records / sums declaration and construction
• Inline lambdas (x:n>n;+x 1)
• Use imports use "file.ilo" [names]
• Tool declarations tool name "desc" params>ret
• Literals numbers, strings (with escape sequences), lists, maps, true, false, nil
• Comments -- to end of line

Versioning

Versions track ilo's grammar shape. Starts at 0.12.0 matching ilo's release line. A new minor version goes out when the grammar adds nodes (new ilo syntax); a new patch when only queries or bindings change.

References

• Tree-sitter docs: tree-sitter.github.io/tree-sitter
• The ilo language: github.com/ilo-lang/ilo
• ilo specification: github.com/ilo-lang/ilo/blob/main/SPEC.md

License

MIT. Matches ilo. See LICENSE.