ochre

A syntax highlighter for OCaml using TextMate grammars and themes, inspired by Shiki.

Installation

opam install ochre -y

Quick start

let theme = Ochre.Theme.nord in
let highlighter = Ochre.load_from_files_exn ["path/to/ocaml.tmLanguage.json"] in
let html = Ochre.to_html highlighter ~theme ~lang:"ocaml" source_code

Load any TextMate grammar with tm-grammars

tm-grammars packages a collection of TextMate grammars for OCaml, so you can load grammars in ochre without managing JSON files on disk.

Install the bundled grammar package:

opam install tm-grammars -y

Then load a grammar from OCaml and create a highlighter:

let theme = Ochre.Theme.nord in
let highlighter = Ochre.load_exn [ ("ocaml", Tm_grammars.ocaml) ] in
let html = Ochre.to_html highlighter ~theme ~lang:"ocaml" "let x = 42"

Output formats

ochre can render highlighted code to several output formats (also called backends):

• HTML — Self-contained <pre><code> blocks with inline styles or CSS classes. Supports multi-theme via CSS custom properties, line numbers, and configurable class prefixes. See rendered example.
• SVG — Standalone <svg> elements with monospace <text> and per-token <tspan> styling. Open preview: SVG rendered example. Source: .svg file.
• ANSI — 24-bit color escape sequences for terminal display.
• LaTeX — \textcolor commands inside an ochrehighlight environment. Requires the xcolor and soul packages. See rendered PDF (source: .tex file).

All backends share the same interface: create a highlighter, pick a theme, and call the corresponding to_* function.

Documentation

• Library API
• Command-line reference

Contribute

Set up the development environment:

make init

Build the project:

make build

Run the test suite:

make test

You can also preview highlighted output in a browser with make test-browser, which serves a sample on port 5000.

Credits

• Inspired by Shiki by Pine Wu and Anthony Fu
• Uses textmate-language and ocaml-oniguruma by Alan Hu