Pony

Embed You a ponyc for Great Good

Sean T. Allen — Tue, 14 Apr 2026 01:44:13 +0000

The ponyc command you run every day is a main() function with a terminal-width detector glued to it. The actual compiler is a library called libponyc. ponyc is a wrapper around that library, and the wrapper is 149 lines of C.

That's the setup for this post. The Pony compiler is a library and you can link against it. And because you can link against it, you can build your own tools. And if you want your tool to be one binary instead of a ball of loose dependencies, you want libponyc-standalone.

Last Week in Pony - April 12, 2026

Sean T. Allen — Sun, 12 Apr 2026 12:46:58 +0000

I'm going to be traveling a lot during the next couple weeks, so our theme song this week is Willie Nelson's "On the Road Again". A true classic. And for a true story: once upon a time I was a young child and met another kid while we were both sitting on Willie's lap at his 4th of July picnic. Years later, I met him again at a bar in NYC when he came up from Texas to hang out with a good friend who was one of my best friends. Small world, right? Willie Nelson, bringing together awesome people since the time of the dinosaurs.

All that aside, we have some great stuff as usual happening in Pony land. ponyc 0.63.1 is out and has safety-related fixes you need. ponylang/postgres 0.3.0 is a monster of a release. A pile of networking libraries went out that you'll want to grab. And there's a whole pitch to make about LLMs and Pony. Let's dig in, because it all just fucking rocks. Get on board this train while there is still time. That's what I'm saying. Get the fuck on board. Oh, and Cloudsmith has throttled us until the end of the day today UTC so, sorry, you can't download any prebuilt binaries until that has lifted.

Claude You Some Pony for Great Good

Sean T. Allen — Sat, 11 Apr 2026 00:42:30 +0000

Here's how it is:

Two months ago I wrote about teaching Claude to write Pony. That post was about the process — mentoring an LLM like a junior developer, building up engineering principles, establishing review loops. Today, I'm here to talk about the LLM skills I've been working on. They're in ponylang/llm-skills, and if you're working on Pony with an LLM, you should try them.

Pony's Postgres Driver Grows Up

Sean T. Allen — Fri, 10 Apr 2026 03:10:18 +0000

Pony has had a Postgres driver since 2023. It didn't do much for most of those three years. That's been changing over the last couple of months.

Last Week in Pony - April 5, 2026

Sean T. Allen — Sun, 05 Apr 2026 12:17:15 +0000

This week's theme song was pulled directly from the pool of "things to appeal to Sean musically." I give you "Apocalypse" by The Darts. Man, this one is great. Big week to go with it. ponyc 0.63.0 is out and you need to update. ponylang/hobby threw out its middleware and rebuilt around interceptors. And there's a whole repo of Claude Code skills for Pony. Three big things and I'm excited about every one of them. Let's go.

Last Week in Pony - March 29, 2026

Sean T. Allen — Sun, 29 Mar 2026 12:47:20 +0000

ponyc 0.62.1 is out and you need to update. There's a type system soundness hole in there, a Windows crash that we didn't fully nail last time, and a bunch more. Beyond ponyc, ponylang/hobby threw out its old handler model and rebuilt it around actors the way Pony wants you to build things. Big week. Let's crank up an oldie but a goodie, "Son of a Pig Farmer" by Krylls, and get into it.

Pony Gets an Embedded Linker

Sean T. Allen — Wed, 25 Mar 2026 17:30:01 +0000

As of ponylang/ponyc 0.61.1, the compiler carries its own linker. When you compile a Pony program on Linux, macOS, or Windows, ponyc no longer shells out to an external tool to produce your binary. It calls LLD directly, in-process, using the same LLVM infrastructure it already uses for code generation. Cross-compilation to Linux targets works the same way. The compiler is more self-contained than it's ever been, and cross-compilation just got a lot simpler.

Pony Gets a Template Engine

Sean T. Allen — Sun, 22 Mar 2026 17:02:09 +0000

If you've been following along, you know the story. Lori for networking. Stallion for HTTP. JSON back in the standard library. Pony's web development stack is coming together piece by piece. But a web stack that only speaks JSON is an API server with aspirations. At some point, someone is going to want an actual page.

ponylang/templates handles that.

Last Week in Pony - March 22, 2026

Sean T. Allen — Sun, 22 Mar 2026 12:57:17 +0000

ponyc 0.62.0 is out and you should update. There are bug fixes in there that matter, including one that was quietly breaking SSL hostname verification. Beyond that, there's a new multipart MIME parser, four new patterns, and pony-lsp landed in Helix. Let's get into it, but first, fire up this week's theme song: "Bloody Mary Morning" by Willie Nelson. Bob Wills might still be the king, but Willie is certainly in the royal court. Oh, and be prepared for lots of homework.

Persistent Data Structures for Concurrent Programs

Sean T. Allen — Wed, 18 Mar 2026 17:23:38 +0000

In my last post, I mentioned that the new json package uses persistent data structures under the hood. Every JsonObject is backed by a CHAMP Map. Every JsonArray is backed by a HAMT Vec. I glossed over why, and I want to fix that.

Pony Gets a New JSON Library

Sean T. Allen — Sun, 15 Mar 2026 23:21:19 +0000

For the first time in three years, Pony has a json package in its standard library. And this one has some tricks the old one never did.

Pony Networking, Take Two

Sean T. Allen — Sun, 15 Mar 2026 23:21:19 +0000

Pony's standard library has a networking package. It works. If you're writing a simple TCP server or client, it'll get you there. But if you've ever tried to build something serious on top of it, something with real protocol logic, backpressure that you control, or TLS upgrades mid-connection, you know where the walls are.

I hit those walls years ago at Wallaroo. We ended up forking the standard library's TCP code and writing our own. That experience is where lori came from.

Stallion: An HTTP Server Built Different

Sean T. Allen — Sun, 15 Mar 2026 23:21:19 +0000

Last week I wrote about lori and the architecture behind Pony's new networking stack. The short version: your actor is the connection, the protocol machinery is a class you own, no hidden internal actors between you and the socket. If you haven't read that post, go do that first. Everything here builds on it.

Stallion is an HTTP/1.1 server built on lori. Red has been running benchmarks comparing it against the old http_server package. Here's what he found, using 50 concurrent connections:

16-byte response body:

| Metric | http_server | stallion | |-------------|-------------|----------| | Requests/s | 441,570 | 710,416 | | 50% Latency | 106µs | 49µs | | 75% Latency | 125µs | 84µs | | 90% Latency | 151µs | 97µs | | 99% Latency | 1.89ms | 1.45ms | | Transfer/s | 34.11MB/s | 54.88MB/s|

100KB response body:

| Metric | http_server | stallion | |-------------|-------------|----------| | Requests/s | 160,052 | 192,069 | | 50% Latency | 254µs | 211µs | | 75% Latency | 375µs | 315µs | | 90% Latency | 0.97ms | 0.9ms | | 99% Latency | 3.07ms | 2.69ms | | Transfer/s | 15.27GB/s | 18.33GB/s|

A few caveats. These numbers only mean something relative to each other. The server and the wrk client were running on the same machine over localhost with keep-alive enabled, so don't go comparing them to your favorite web framework's benchmarks. And this is actually the best-case matchup for the old stack. The benchmark is dead simple. Turn off keep-alive and most of the difference disappears because socket open/close overhead dominates everything else.

Teaching Claude to Write Pony

Sean T. Allen — Sun, 15 Mar 2026 23:21:19 +0000

I'm not really sure how to tell the story of me teaching Claude to write Pony, so I'm just going to tell it and see how it goes.

A year ago, every LLM I tested on Pony produced the same thing: a weird Python/Pony hybrid that didn't compile and didn't understand Pony's semantics. I'd ask for a program that prompts you for your name and prints "Hello {name}." Simple stuff. They all failed miserably. So when I sat down two weeks ago to try again with Claude Code, my expectations were modest.

Last Week in Pony - March 15, 2026

Sean T. Allen — Sun, 15 Mar 2026 11:30:15 +0000

What a great week in Pony! So much fun! Let's have two happy time theme songs for this week! We've got a packed ponyc release, BSDs are back in CI, json-ng landed in the standard library, and there's a brand new library for building LiveView UIs. This bunch is ripe for the picking.

Last Week in Pony - March 8, 2026

Sean T. Allen — Sun, 08 Mar 2026 09:45:05 +0000

This week's theme song is "Tennessee Quick Cash" by the incredible Charley Crockett. No secret meaning this time. I love Charley Crockett, I'm seeing him tonight, and I'm gifting you the love. A big week to go with it: a blog post about Pony's networking future, a massive ponylang/templates release, and the first release of ponylang/courier.

Last Week in Pony - March 1, 2026

Sean T. Allen — Sun, 01 Mar 2026 12:15:37 +0000

This week's theme song is Rawhide and it's so good, we are gracing you with 3 different versions. And this week calls for multiple versions because it has been a big week:

ponyc 0.61.0 shipped with a new \exhaustive\ annotation for match expressions
Three new libraries hit their first releases
Eight Pony patterns were published
The website got a top-to-bottom reorganization

Last Week in Pony - April 10, 2017

Colin O'Brien — Sun, 22 Feb 2026 15:32:46 +0000

Last week's Pony news, reported this week.

Last Week in Pony - May 28, 2017

Sean T. Allen — Sun, 22 Feb 2026 15:32:46 +0000

Last week's Pony news, reported this week.

Last Week in Pony - February 22, 2026

Sean T. Allen — Sun, 22 Feb 2026 13:14:45 +0000

Crank up this week's theme song — Horse Outside by the Rubberbandits — and settle in. Big week. We welcomed a new committer, shipped three brand-new libraries, and put out ten releases across five projects. There's also a persistent HashMap bug fix that enabled json-ng to drop its custom null type, three new Pony patterns, and a blog post about teaching Claude to write Pony.