The cost of interop in WASM is currently very big as there's no way to pass non-numeric data to the host language without explicit conversion, which is very slow. WASI is trying to address this but as far as I know it's very far from being used by WASM language implementations. Most WASM implementations , by the way, are completely experimental at this point... listing 30 languages as supporting WASM seems highly misleading to me, as someone who has played around with a few languages compiling to WASM. I would say that only C, C++ and Rust have decent support. Even the Go support is currently extremely experimental and limited when compiling to WASM, and that would be the next "best" option. Lack of GC is a huge problem here and the current approach seems to be to allow runtimes to only optionally provide one.
