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 heavily optimized for 3D: it can compile dazzling web effects down to a little over a hundred kilobytes, 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.