Syntax-highlight emitted MIR as Rust

[camelid]

This would make it much easier to read the output since MIR is syntactically very similar to Rust.

[shepmaster]

If you want to experiment with this, you can poke around with Prism to see how to inherit the existing Rust logic, I think.

[camelid]

Can you give some advice on how I should start to approach this? I haven't done much in the way of SPAs and I also am new to working on the Playground :)

[shepmaster]

Prism is what is used for syntax highlighting outside of the editor (which is Ace). It states:

Define new languages or extend existing ones. Add new features thanks to Prism’s plugin architecture.

I see a few paths:

1. Get some Prism-related setup working completely separately from the playground, then try to create a new "language" that extends from the Rust config. Once something is working-ish, try to merge it back into the playground.
2. Same idea, but different order. Try extending the existing code in ui/frontend/highlighting.ts around Prism.languages.rust_mir to use the same things as the Rust logic.

I don't know much about Prism beyond what you'll see in highlighting.ts, but I can try and answer questions about the Playground's special setup(s) as you hit them.