Embed Rhai-rs in Glicol for sample-level music/DSP live coding in web browsers

[chaosprint]

first, I would like to thank all the contributors of rhai especially @schungx

TL;DR

I have been exploring the possibility to embed a script language into my project glicol (graph-oriented live coding language) is a computer music language and an audio DSP lib written in Rust:

o: sin 440 >> mul 0.2 // hello world

with rhai script, you can now write code like this to make music in web browsers:

o: script `
    output.pad(128, 0.0);
    for i in 0..128 {
        output[i] = sin(2*PI()*phase) ;
        phase += 440.0 / sr;
    };
    while phase > 1.0 { phase -= 1.0 };
    output
` >> script `
    output = input.map(|i|i*0.2);
    output
`

• try it on: https://glicol.org
• source code: https://github.com/chaosprint/glicol

---

a little bit more on the process

one limitation for Glicol before, and perhaps in many other computer music languages/live coding languages, is that there is no mechanism to support sample-level dsp live coding. in Max/MSP, there is an object called ~gen which is probably the most well-known for this purpose.

I have been looking for options for this embedding language and finally landed on rhai.

the syntax of rhai is really intuitive and I think it has merged the syntax sugar of js and rust.

embedding Rhai in Glicol is a very straightforward experience thanks to its well-designed api and docs (rhai.rs)

now, users can write:

a: script `
    output.pad(128, 0.0);
    for i in 0..128 {
        output[i] = sin(2*PI()*phase) ;
        phase += 440.0 / sr;
    };
    while phase > 1.0 { phase -= 1.0 };
    output
` >> script `
    output = input.map(|i|i*0.2);
    output
`

see the interactive example on https://glicol.org/guide#rhai2

from my current testing, for this real-time audio scripting, creating new variables, especially arrays should be avoided.

for now the script node provides outout, input (if there is one), sr and phase to the Scope of rhai, as well as variables from a to z. x0, x1, x2, y0, y1, y2.

I am still exploring the possibility to share a ringbuf in rhai Scope; some functions such as random can also be useful.

if you are interested, please give me some feedback here or on the github repo of glicol:
https://github.com/chaosprint/glicol

cheers!

[schungx]

some functions such as random can also be useful.

There is a rhai-rand crate. :-)

[schungx]

creating new variables, especially arrays should be avoided.

Yes, Rhai arrays hold Dynamic values. There are no "typed arrays" in Rhai (other than BLOBs which is a byte array).

If you need a typed array, you'd need to register its API.