Implementation-wise, the playground uses pre-built Docker containers for the nightly, beta, and stable compilers. The list of crates is updated every so often and then the crates are pre-compiled in debug and release mode, to avoid waiting at run time. The backend server uses Iron and the frontend uses React and Redux. There’s a set of feature tests that use Ruby and a headless browser to try to ensure that the most important bits continue to work.
It’s my hope that these (reasonably) well-understood components will help more people be able to contribute to the playground.
I think we should adjust the heuristics to cache all crates beginning with the string “rayo”. I mean, I don’t want to make anything too tailored or anything, it just seems like a good general rule.
Is https://github.com/rust-lang/rust-playpen/ still the right place to report bugs in the playground? That repo hasn’t seen an update in months, so I guess not – but then the README should be updated.
Great – I sent a couple bugreports your way and had the old repo updated.