Stream: wit-bindgen

Topic: ✔ dropping unions

Lann Martin (Aug 21 2023 at 14:30):

I think we should remove unions from WIT: https://github.com/WebAssembly/component-model/issues/236

Lann Martin (Aug 21 2023 at 14:32):

I suppose if we want to maintain the 1:1 mapping from CM types then that would entail removing them from the CM type system as well.

Lann Martin (Aug 21 2023 at 14:35):

I'm slightly skeptical of tuples as well, but I think a lot more languages have a "natural" representation of tuples than unions.

Joel Dice (Aug 21 2023 at 14:45):

:thumbs_up: unions are awkward in Python, too.

Alex Crichton (Aug 21 2023 at 14:49):

commented as well, but I agree they'd be good to remove :+1:

Lann Martin (Aug 21 2023 at 15:36):

Given the feedback from Alex and Luke on the issue, I cross-posted reference issues to wit-bindgen and wasmtime for visibility

Karel Hrkal (kajacx) (Aug 21 2023 at 18:08):

I have not even used the wit unions, for me, variant is just better.

Lann Martin (Aug 25 2023 at 17:23):

For those following along at home, unions have been dropped from the spec and from wasm-tools, with PRs ready in wit-bindgen and wasmtime just awaiting dependency releases

Notification Bot (Aug 26 2023 at 16:07):

Scott Waye has marked this topic as resolved.

Notification Bot (Aug 26 2023 at 16:09):

Scott Waye has marked this topic as unresolved.

Scott Waye (Aug 26 2023 at 16:09):

Sorry, marked wrong topic as resolved.

Lann Martin (Aug 28 2023 at 12:26):

Actually, with https://github.com/bytecodealliance/wasmtime/pull/6913 merged, this is done. Farewell unions, we hardly knew used thee.

Notification Bot (Aug 28 2023 at 12:26):

Lann Martin has marked this topic as resolved.

Last updated: Jan 10 2026 at 02:36 UTC