hckrnws
Show HN: What if your synthesizer was powered by APL (or a dumb K clone)?
by octetta
I built k-synth as an experiment to see if a minimalist, K-inspired array language could make sketching waveforms faster and more intuitive than traditional code. I’ve put together a web-based toolkit so you can try the syntax directly in the browser without having to touch a compiler:
Live Toolkit: https://octetta.github.io/k-synth/
If you visit the page, here is a quick path to an audio payoff:
- Click "patches" and choose dm-bell.ks.
- Click "run"—the notebook area will update. Click the waveform to hear the result.
- Click the "->0" button below the waveform to copy it into slot 0 at the top (slots are also clickable).
- Click "pads" in the entry area to show a performance grid.
- Click "melodic" to play slot 0's sample at different intervals across the grid.
The 'Weird' Stack:
- The Language: A simplified, right-associative array language (e.g., s for sine, p for pi).
- The Web Toolkit: Built using WASM and Web Audio for live-coding samples.
- AI Pair-Programming: I used AI agents to bootstrap the parser and web boilerplate, which let me vet the language design in weeks rather than months.
The Goal: This isn't meant to replace a DAW. It’s a compact way to generate samples for larger projects. It’s currently in a "will-it-blend" state. I’m looking for feedback from the array language and DSP communities—specifically on the operator choices and the right-to-left evaluation logic.
Source (MIT): https://github.com/octetta/k-synth
Marshall Lochbaum's APL-derived language BQN has some nods towards audio synthesis too:
BQN kicks-ass and I've spent hours listening to the Array Cast podcast while in SoCal traffic. I'll check his stuff out with an eye towards the audio stuff.
I'm an APL newb... while I've been writing code-for-cash forever (C, etc.) I've had a long-time interest in APL languages, but I'm just messing around after working on waveform generation for another sound project I have in the works (https://github.com/octetta/skred ... https://youtu.be/L5-3gBpJsAo?si=JdBlntzn4doY-c3s).
While I was working on this I remember the first book I saw in the public library on computer programming was about APL (probably sometime around 1976)... I didn't have access to a "real computer" for another year after that and no APL for decades, but some ideas stick around, LOL.
Wowie! I'M NOT WORTHY! Cool stuff!
It’s not my language, to be clear! In fact I’ve never even tried it… my array programming experience so far has mostly been with J.
Doesn't matter. Just happy people are doing weird stuff like this and appreciate the share. I looked at a bunch of APL-ish implementations and kind of ran with the K-simple code (links on the repo). What background do you come to J from? Another programming language? How do you like it?
> What background do you come to J from? Another programming language?
Yes, I’m very fond of trying out different languages. My main language for personal projects is Haskell.
> How do you like it?
I haven’t used J for a while, actually, but I recall finding it a bit confusing, especially when rank manipuations are involved. It has a larger vocabulary than most array languages, which I felt made it hard to learn. It was great fun though!
Fun. I've lost count of the languages I've learned and gotten paid to use over the years, but it's mostly very exciting to add a new one to the list.
Haskell is one I haven't used yet. The closest I've come to that is a weekend fling with OCaml... much respect for the ML work though!
I hear you for the complexities in J though. I've intentionally limited k-synth to single letter upper case variables and the verbs are also one character... I might regret this at some point.
Have fun! It makes the world a better place!
Could a K-style array language be a practical way to design audio waveforms and DSP patches?
that's what i'm playing with... thoughts?
I fixed a few broken examples in the README.md file but I don't have the related readme.html file used in the web app getting automatically updated, so they're out of sync at the moment.
How do we get it to play Kompressor? https://youtu.be/9tlA0IyKjiI
Wowie... Jart commented! I'm on it my friend. Certainly sequencing is a good thing to add.
I have a CLI and desktop versions on github (all MIT license)
https://github.com/octetta/k-synth https://github.com/octetta/ksynth-desktop/
it's been a blast to play with... and a great excuse to learn array languages
A warning... if you save a setup to JSON, it naively stores the generated waveforms put in slots and the notebook, so the files can become quiet large. I have a plan to just keep the code behind the waves and regenerate the waveforms at load time.
On the C-side, I'm going to add a UDP listener to the code so I can send k-synth incantations live from Emacs (something I did for my skred program at the suggestion of an Emacs user). Let me know if anyone wants to know about this when it's usable. On the desktop app side, I use miniaudio (thank's Macron) so this is portable to the usual suspects. I also made a single header file cross platform midi library which I have some devious plans for in this space. Stay tuned.
Pretty cool, one suggestion for the site would be to have templates you can quickly load, copy, edit, and share. Sort of like strudel.cc has!
At any rate, in case it's hard to see, definitely try loading the dm-bell.ks patch, putting it in slot one so the melodic pad can play it... it's quick and dirty to see what's capable in a few keystrokes... although I'm sure the PD and ChucK and SC and ... wizards could put me to shame in a showdown, LOL.
i wimped out and just have the patches being loaded from my github repo. good suggestion though.
Did you know you can embed strudel?
Strudel (and PureData, and ChucK, and SuperCollider, and AMY) are all great projects, but they weren't scratching my itch, so after I got laid off from a FAANG role, I rage/anxiety started writing code for stuff fun-ner than writing code for radios and routers and satellites... this is where my cortisol / dopamine lead me. No disrespect to those other projects... all have been inspirational and are a heck of a lot more "respectable" than my playground code.
I don’t think this is relevant to my analogy there, what were you thinking here?
You are right but I wondered if octetta had considered combining his ui with strudel. I am fascinated by it and have been attempting to riff off it and create new creative interfaces.
I'll take a look... it's probably not obvious, but the language engine is actually written in C and emscripten-ed to WASM, so I've already crossed several bridges to get this done. Absolutely riff off this interface... would love to see what you can make. My stuff is MIT licensed, so tear it up! On a side note, I was able to meet Sam Aaron of SonicPi / Tau5 at Goarmire back in September which was cool... he teased us with Super Collider in JS then and since, he's crossed the finish line on that stuff. We live in amazing times! Have fun!!!
That's a great story. It's beautiful you are building on the shoulders of giants and putting it out there for others to build upon. Very exciting times, indeed!
See also: Stanley Jordan, "APL For Music".
https://dl.acm.org/doi/pdf/10.1145/75144.75174
(!!!)
(Wait, what? That Stanley Jordan?) (Yep.)
Wow! I had no idea, will look here for inspiration too. Thanks!
This is great
thanks!
> ...and the right-to-left evaluation logic.
The evaluation order doesn't matter as much as you don't really know what kind of function/operator you have at parse time so have to do a bunch of shenanigans to defer that decision until runtime while still keeping it efficient. Kind of fiddly to get right but once it works, it just works.
Claude and me (and a ton of decades old research) pretty much figured out all the complications in the APL parse/eval stack (https://github.com/dan-eicher/AiPL).
I'm looking forward to checking out your stuff...
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