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Comment by tcfhgj | Hacker News Reader

> The #1 thing for the Rust project to do is make Rust faster to compile.

#0 get rid of the orphan rule

btw. That could actually make it slower to compile. The compiler uses the orphan rule to short circuit some checks IIRC.

Nevertheless, people in the project are trying to figuring out a way to relax the rule while still maintaining coherence, so this might happen some day.

there are good reasons, obviously, but it's my #1 PITA, #2 is comptime type introspection (it looks like @yara-blue is making some progress, so fingers crossed)

BTW: cheers, we should grab a beer some day :)

We should ;)

What's the orphan rule?

Rust doesn't let you write an impl a trait that wasn't declared in your crate for a type that wasn't declared in your crate. At least one of the two needs to be locally declared. This makes splitting projects into multiple crates harder than it could be, but on the other hand it makes the crates ecosystem less brittle than it otherwise would be.

Some people propose relaxing this rule for "workspaces" (local projects with multiple crates that are not published individually). I haven't researched whether that would be technically feasible.

It absolutely should be relaxed for workspaces.

Workspaces are a great way to architect larger projects and monorepos, and they'd at least be internally consistent.

If you built two impls, your compiler wouldn't know which to pick. Or to phrase it differently, if you wanted to be able to choose the right one, it wouldn't be 'orphan impls', it would be 'orphan impls plus some selection mechanism'. E.g. Scala implicits. And once you have Scala implicits, non-orphan impls probably start looking like a pretty sweet alternative!

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