Wasm build, implement js promises an rust futures

[Thomas-Langlais]

https://rustwasm.github.io/wasm-bindgen/reference/js-promises-and-rust-futures.html

The wasm build needs to be asynchronous so that the demo can force the program to exit. This is for the case when the program loops forever.

[Thomas-Langlais]

If i want to stop the interpret loop. It needs to be aware of a stop flag that we can set outside of the async loop to trigger it to stop the execution.

It needs to have a condition in here

impl<'a> Interpret<'a> for SyntaxNode {
    fn interpret(&self, context: &mut ExecutionContext) -> Result {
        // add the exit condition here

        match self {
            Self::If(node) => node.interpret(context),
            Self::Statements(node) => node.interpret(context),
            Self::Statement(node) => node.interpret(context),
            Self::For(node) => node.interpret(context),
            Self::While(node) => node.interpret(context),
            Self::Continue(_) => Ok(InterpretedType::Continue),
            Self::Break(_) => Ok(InterpretedType::Break),
            Self::Variable(node) => node.interpret(context),
            Self::Factor(node) => node.interpret(context),
            Self::Unary(node) => node.interpret(context),
            Self::Term(node) => node.interpret(context),
        }
    }
}

This way, whenever the interpret loop hits a syntax node, we can check the exit state and exit early if requested.

[Thomas-Langlais]

Scratch that, it won't matter because running wasm in the main thread (e.g. executing the tlang code) will always block input. in order to not block the main thread, I will need to run the interpreter on a web worker. This way, we can send messages to execute and stop the interpreter from the main thread.

[Thomas-Langlais]

Unfortunately even running the interpreter would not solve the problem.

If I did implement the interpreter in a webworker, and executed an infinite loop in a promise. The web worker thread wouldn't be able to respond to a new postmessage event because it would still be looping infinitely.

There is no way around this problem in a wasm environment. However, we could detect that the webworker is not responsive, and could add a feature to reset the terminal.