Zeeshan Lakhani (Feb 23 2023 at 18:05): Zeeshan Lakhani (Feb 23 2023 at 18:05):Is there a way to unwrap_list and know the inner wasm:component:types:Type associated with it with the inner handle? I'm running into this scenario trying to map some things with lists of lists (nested lists)? I'm probably missing something. I didn't find a good test w/ inner lists and wit as well.
Pat Hickey (Feb 23 2023 at 18:11):good q, the only test i can find that uses list<list<string>> is in wit-bindgen
Pat Hickey (Feb 23 2023 at 18:12):https://github.com/bytecodealliance/wit-bindgen/blob/main/tests/runtime/lists/wasm.rs#L100
Pat Hickey (Feb 23 2023 at 18:14):when using wit-bindgen, we present the list as a Vec<Vec<String>>, so the api definitely works. you can use cargo expand to see how the wasmtime::component::binden! macro generates the code that goes from component::Val to that
Pat Hickey (Feb 23 2023 at 18:15):does that answer your question? or is there something particular about the types representation of lists that is missing here
Pat Hickey (Feb 23 2023 at 18:17):it looks to me like if you have a ty: Type and its a list, the elem type is then ty.unwrap_list().ty()
Zeeshan Lakhani (Feb 23 2023 at 18:22):Thanks @Pat Hickey. I'll double check the bindgen. I was using ty.unwrap_list().ty() while trying to reuse the echo component stuff in the wasmtime repo test suite. It was just giving me the inner list handler at index 0 (first run returns 1). But, I think I maybe got it. :)
Zeeshan Lakhani (Feb 23 2023 at 18:28):@Pat Hickey a Q in addition then. In the current wit / component spec, would there be any way to encode heterogeneous lists? Or is that eve something to think about :)
Pat Hickey (Feb 23 2023 at 18:28):theres no dynamic types in component model, so youd need to make an enum of the possible variants in your hlist
Pat Hickey (Feb 23 2023 at 18:29):theres also no recursive types
Pat Hickey (Feb 23 2023 at 18:30):these do eliminate some cool possibilities, but theyre reasonable restrictions for a lot of "real world" programs for now, and make it a lot more tractable to ship this thing :)
Zeeshan Lakhani (Feb 23 2023 at 18:33):Yep, figured @Pat Hickey. I'm writing an IR from something that had recursive types and mapping that, with runtime checking, to wasmtime:component Vals. Encoding the enum of variants is next on my list.
Zeeshan Lakhani (Feb 23 2023 at 19:01):Thanks again @Pat Hickey
Last updated: Dec 23 2024 at 12:05 UTC