Hyades

LaTeX math as pure Unicode text. For terminals, code comments, emails, and everywhere rich formatting isn’t a thing.

What Is This?

Hyades takes standard LaTeX math like this:

$$
  f(x) = \overbrace{\sum_{k=0}^{n} \frac{f^{(k)}(a)}{k!}
           (x-a)^k}^{\mathit{Taylor polynomial}}
       + \underbrace{R_n(x)}_{\mathit{Remainder}}
$$

and renders it as multi-line Unicode text:

             𝑇𝑎𝑦𝑙𝑜𝑟 𝑝𝑜𝑙𝑦𝑛𝑜𝑚𝑖𝑎𝑙
         ╭───────────┴───────────╮
           𝑛      (𝑘)
          ───    𝑓   (𝑎)         𝑘
  𝑓(𝑥) =  ╲     ───────── (𝑥 − 𝑎)  +   𝑅 (𝑥)
          ╱⎽⎽      𝑘!                   𝑛
         𝑘 = 0                       ╰───┬───╯
                                     𝑅𝑒𝑚𝑎𝑖𝑛𝑑𝑒𝑟

or plain ASCII if you ask it to:

           n      (k)
          ---    f   (a)         k
  f(x) =  \     --------- (x - a)  + R (x)
          /__      k!                 n
         k = 0

It’s a native CLI binary written in pure C. As such it is extremely fast and doesn’t require any additional dependencies. Linux, MacOS, and Windows, and Web (WASM) are all supported out of the box.

Try it in your browser → – interactive WASM playground with tutorials and a full syntax reference. No installation required.

Features

Math – 95% LaTeX compatible

Fractions, roots, integrals, summations, products, limits, matrices, piecewise functions, aligned equations, Greek letters, auto-scaling delimiters, overbrace/underbrace, accents, primes, binomial coefficients, extensible arrows, equation tags, you name it… Paste your existing LaTeX and it just renders.

Beyond math

• Tables – \table with \row/\col, 6 frame styles (single, double, bold, rounded, dotted, none), padding, alignment, column spans
• Lists – \fancylist builds a list using Markdown syntax
• Layout – Flex-like hbox/vbox containers with auto/intrinsic/fixed-width children, horizontal and vertical alignment
• Text formatting – \textbf, \textit, \texttt, \verb|...|
• Paragraph layout – Justified text with novel monospace-optimal line breaking, or just vanilla left aligned; hyphenation
• Rules – \hrule/\vrule with auto-sizing and smart automatic junction intersection
• Macros – User-defined with parameters and variable scoping
• Computation – Variables, arrays, loops, conditionals, lambdas – a complete programming language with a stack-based instruction machine
• ASCII mode – Full ASCII fallback for environments without Unicode
• Syntax highlighting – For vscode, Helix, and Neovim
• Inline error diagnostics – For vscode, Helix, and Neovim

Installation

Pre-built binaries

Download from Releases (macOS, Linux, Windows), then run the install script:

# Linux / macOS
chmod a+x install.sh
./install.sh

# Windows (PowerShell)
.\install.ps1

The script will:

• Install hyades, cassilda, hyades-cmp, and add to PATH
  • Unix: $HOME/.local/bin
  • Windows: $env:USERPROFILE\bin
• Integrate into Helix and Neovim if installed
• Render documentation files at
  • Unix: $HOME/.local/share/hyades/docs
  • Windows: $env:USERPROFILE\AppData\Local\hyades
• Typeset something to verify the installation

This adds hyades, cassilda, and hyades-mcp to your PATH and integrates the tree-sitter grammar and LSP server into Helix and/or Neovim if installed.

Build from source

cmake -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build
# → build/hyades, build/cassilda

Usage

# Render LaTeX from stdin
echo '$$\sum_{i=1}^n i^2$$' | hyades

# Render a source file
hyades equations.hy

# ASCII-only output
echo '$$\int_0^1 f(x) dx$$' | hyades --ascii

# Run an interactive-mode Hyades program
hyades -c matrix_rain.hy

The two binaries

# Render a labeled section to stdout
cassilda render notebook.cld section_name

# Process all sections in-place
cassilda process notebook.cld

MCP server

An MCP server lets AI assistants render math expressions on the fly.

Remote – no install, Cloudflare Worker:

# Claude Code
claude mcp add hyades --transport http https://hyades-mcp.apg.workers.dev/mcp

# Claude Desktop / Cursor / Windsurf -- add to config:
{ "mcpServers": { "hyades": { "url": "https://hyades-mcp.apg.workers.dev/mcp" } } }

Local – offline, native binary (included in releases):

# Claude Code
claude mcp add hyades /path/to/hyades-mcp

# Claude Desktop / Cursor / Windsurf -- add to config:
{ "mcpServers": { "hyades": { "command": "/path/to/hyades-mcp" } } }

Example: Reason with Claude about math in the terminal

Editor support

The install script automatically configures any installed editors. Manual setup is also possible – config files are in editor-configs/ within the release.

Helix and Neovim get full integration out of the box:

• Syntax highlighting via tree-sitter (.hy and .cld files)
• Error diagnostics – inline and in the gutter
• Go-to-definition – jump to macro and label definitions
• Hover – documentation pop-ups for commands and macros
• Completions – context-aware suggestions
• References – find all usages of a symbol

A VS Code extension is also available. (I’m yet to polish and publish it, should be a matter of days.)

Beyond all this

Hyades has an bytecode compiler and a stack-based VM (called Subnivean), which allows you to write pretty much any computational code to support your macros and rendering. Two fun examples are included in the release package. The first is the Matrix code effect for the terminal

And the second one is interactive Game of Life

Which is also a direct proof of Hyades’ Turing-completeness.

AI Disclosure

I started this project before the era of AI, so about half of it was made without it, and later Claude helped me greatly to implement features that would take me weeks on my own, especially with a small baby to take care of, and to bring this project to completion.