The difference in Rust's case is that whenever anything was removed it was replaced with something that was better designed. It provided escape hatches available to allow for workarounds (ie. unsafe, and a nice FFI), and to allow C libraries to bridge the gap while the ecosystem was still developing.

That’s exactly the kind of answers I got instead of giving me one good engineering reason on why primes were made forbidden just like this. Thanks for the demonstration.

The actual reason is probably "when people use primes, they post code that gets syntax-highlighted by tools that don't know about primes, and this results in Elm code looking broken and stupid."

Which is not a good reason to ban them completely from one release to the next. It only shows that they don’t really care about their users that much.

Rust has FFI that doesn't shit the bed lol