[v2] Provisional WASM build

[ArtemGr]

Should try to build the MarketMaker into the WASM.

At this stage it will probably be hard due to C library dependencies (will be much easier to do for a purely Rust project).

But we should test the waters and if possible, create a WASM-compiled portion of the code. This WASM-compiled portion will probably match the Purely functional core.

[ArtemGr]

https://github.com/yeletech/libbolt with

rustup target add wasm32-unknown-unknown --toolchain nightly
cargo +nightly build --target=wasm32-unknown-unknown

with

rustup target add wasm32-unknown-emscripten
# https://github.com/raphamorim/wasm-and-rust#installing
cd
curl https://s3.amazonaws.com/mozilla-games/emscripten/releases/emsdk-portable.tar.gz | tar -zxv -C ~/
cd ~/emsdk-portable
./emsdk update
./emsdk install sdk-incoming-64bit
./emsdk activate sdk-incoming-64bit
cd ~/libbolt
. ~/emsdk-portable/emsdk_env.sh
cargo +nightly build --target=wasm32-unknown-emscripten

(Having now installed Emscripten, I think we should stick to wasm32-unknown-unknown to increase portability and reduce the complexity of the build. That is, the WASM part can be not only portable itself, but also be build in a portable way, with just the basic Rust installation. Requiring Emscripten will make building much harder, which might have a negative effect on developers and testers and power-users).

P.S. With

export PKG_CONFIG_ALLOW_CROSS=1
cargo +nightly build --target=wasm32-unknown-emscripten

[ArtemGr]

Interesting to see the idea of WASM-boxed execution getting traction: https://blog.cloudflare.com/cloudflare-workers-as-a-serverless-rust-platform/

[ArtemGr]

wasm-bindgen and thread-locals: rust-lang/rust#54951

[ArtemGr]

A [Purely]-functional candidate for WASM is

// [functional]
pub fn bitcoin_address (coin: &str, addrtype: u8, rmd160: [u8; 20usize]) -> Result<String, String>

During the porting I have untangled it from the shared state, making it functional and eligible for WASM.

(i'm sure there are others, but chance is we're not always on a lookout for them).

A curious thing about this function is that it uses C code.
Can we compile it into a small WASM while reusing the C code?

P.S. Another thing to consider is that maybe the stateful code can now be used in WASM as well, given that we'll soon have mutexes in WASM, allowing us to maybe compile the shared state structures (such as MmCtx) to WASM.