Why no recursive types in WIT/component model · general

Stream: general

Topic: Why no recursive types in WIT/component model

Damian Reeves (Apr 05 2024 at 13:32):

The exclusion of recursion in types seems to make it impossible to model tree structures in WIT, or ASTS, or even a simple data format like JSON. Am I missing something? How would I define JSON or SExpressions in WIT?

Lann Martin (Apr 05 2024 at 13:34):

https://github.com/WebAssembly/component-model/issues/56

Recursive Types · Issue #56 · WebAssembly/component-model

There was some discussion on recursive types in WebAssembly/interface-types#137. My takeaway was that recursion would be hard to specify with adapter functions. With adapters punted to a post-MVP p...

Damian Reeves (Apr 05 2024 at 13:35):

Thanks

Lann Martin (Apr 05 2024 at 13:39):

Depending on your exact requirements, the 3 alternatives I'd suggest are:

serialize as e.g. JSON
represent nodes with resources
flatten your recursive type into a list (tricky but potentially most efficient actually, unlikely to be more efficient than a good binary serialization format)

Ramon Klass (Apr 05 2024 at 14:24):

I'm using MessagePack because that is supported by several possible guest languages, but bincode is probably the most efficient format (rust only)

Karel Hrkal (kajacx) (Apr 13 2024 at 06:35):

I'm serializing a (possibly) recursive structure as JSON and sending a string across the wit boundary and it's working great.

Last updated: Dec 23 2024 at 12:05 UTC