Igropyr

Origins

The Igropyr project contains two parts: Igropyr on the server, and Goeteia in the browser.

Igropyr began in 2018. Out of love for Scheme, I was looking for a modern Scheme web server I could actually run in production — not a proof of concept content to stay in academia — and I found nothing.

Back then, and still today, Scheme web servers stop at raw string concatenation to build a request and its response. They lack the modern conveniences — proper JSON responses, concurrency, asynchrony, and the like — that a real application backend needs.

So I improvised. I tried Apache calling out to CGI. Then, inspired by Node, I wrote a first thin wrapper over libuv. That was Igropyr's earliest prototype.

In the years that followed I came to know Erlang, and took its ideas to heart: message passing, and let it crash. Around that time Swish had built the earliest Erlang-style system on Chez Scheme — but its network programming still lived in that same primitive, string-concatenation world.

Swish is what convinced me. Inspired by it, I decided to rebuild Igropyr from the ground up.

Today Igropyr goes further than that Erlang prototype ever did. When a handler crashes or a request times out, the server can tell the client that the request went wrong — and hand the choice back to it: retry, retry with different parameters, or stop. In practice this shortens how long a user waits, and it makes server-side failures invisible from the user's side.

And it carries messages as s-expressions themselves: when both ends speak Scheme, a request and its reply need no codec at all — the data crosses the wire as it is, exact numbers intact. Scheme, at last, has a JSON of its own.

It even supports continuation-based web programming — the functional community's most beautiful daydream. It is no fit for an ordinary form-filling page, but where the work is strongly transactional it lets a single transaction stretch across the wire, held open between the server and the remote client.

By now Igropyr carries everything a modern web server is expected to have: JWT, non-blocking Redis and database clients, a self-forming cluster, hot code swapping, and even BLAS-accelerated vector search…

Goeteia came from another daydream — writing the front end in pure Scheme as well. I tried Scheme-to-JavaScript compilers, but in the end a Scheme compiler built on WebAssembly turned out to be the better choice.

Goeteia, for its part, is a compiler just 50 kB and heavily optimized for 3D. It renders dazzling web effects from Scheme straight to the page on the fly, or precompiles them for more speed and optimization, and it supports programming web games. It also takes a fresh approach to the DOM — in this post-virtual-DOM-tree era, a distinctly Scheme one: macro-based DOM state management, and pretext effects.

The project is entirely open source, free for any use — commercial included. I hope you enjoy it.