Stream: compiler development

Topic: Zig compiler feature parity

Richard Feldman (May 29 2026 at 21:22):

I think we're getting close to feature parity (although obviously not bug parity, ecosystem parity, etc.) with the new compiler, so I wanted to start a thread to talk about what's still missing in terms of compiler features specifically.

Setting aside the platform and package ecosystem, what things does the Rust-based compiler do that the Zig-based one doesn't support yet?

Richard Feldman (May 29 2026 at 21:23):

for example, I know we no longer have the ability to build a web repl

Richard Feldman (May 29 2026 at 21:24):

also the cli repl is not at feature parity

Richard Feldman (May 29 2026 at 21:24):

wasm surgical linking hasn't landed yet

Richard Feldman (May 29 2026 at 21:24):

what else?

Richard Feldman (May 29 2026 at 21:30):

@Jared Ramirez are we missing anything in terms of type checker features you can think of?

Richard Feldman (May 29 2026 at 21:44):

oh we don't have as many things auto-derived yet, like equality might be the only one. Maybe encode too, but I don't think decode

Anton (May 30 2026 at 11:04):

Richard Feldman said:

for example, I know we no longer have the ability to build a web repl

Is that a recent loss? Because we did have a web repl in the playground.

Richard Feldman (May 30 2026 at 11:25):

oh I just mean the current roc-lang.org doesn't have the web repl on there

Richard Feldman (May 30 2026 at 11:25):

not that we can't do repl things in wasm in general :smile:

Jared Ramirez (May 30 2026 at 13:48):

the only type checker thing i can think of is polarity! i have an old branch with it mostly implemented (that’s probably out of date) that i can dust off

Jared Ramirez (May 30 2026 at 13:49):

outside of that, I _think_ we are feature complete in the type checker

Richard Feldman (May 30 2026 at 14:01):

oh yeah, that would be awesome to land! :smiley:

Richard Feldman (May 31 2026 at 14:22):

ok actually after talking with @Jared Ramirez we're gonna try intentionally not doing polarity this time around and see how it goes

Luke Boswell (Jun 01 2026 at 01:07):

Richard Feldman said:

also the cli repl is not at feature parity

I'll have a quick look at this. I think there is a lot of low hanging fruit here, so just putting a small PR together.

Luke Boswell (Jun 01 2026 at 01:09):

Richard Feldman said:

wasm surgical linking hasn't landed yet

I've merged that into zig-16 branch... we can build roc build --target=wasm32 now :octopus:

Luke Boswell (Jun 01 2026 at 03:04):

Found something... the compiler builtins are missing integer bitwise operations

Last updated: Jun 16 2026 at 16:19 UTC