The web APIs are described using the Web IDL and I believe that could be translated to C++ , Haskell and pretty much any language with more or less effort.
In fact I think there are bindings for some languages such Python and Objective C though they are not open. I see no reason why a WASM interface could not be exposed (the code itself could be developed in C/C++ and compiled to WASM)for the web APIs and exposed to the client.