Comment by Tobba_ | Hacker News Reader

Comment by Tobba_ | Hacker News Reader

Parent Full thread

Pre-MIR, I'm fairly sure the people who would touch the type/lifetime checker could be counted on one hand, and it was borderline obfuscated due to all the pointless type theory thrown around.

RFCs would still get rejected as "postponed" if it wasn't possible to implement them (i.e dependent on MIR). Implementability was the deciding factor from what I could see, though compiler improvements would usually render them un-postponed/rejected later.

Overall I think the lack of an actual specification hamstrung it real bad, since everything past one step ahead only existed in peoples heads. And, at least me for me, it can't replace C++ (in every situation) as much as I'd prefer not to have to use that abomination of a language.

> RFCs would still get rejected as "postponed" if it wasn't possible to implement them (i.e dependent on MIR)

Indeed, but postponed emphatically does not mean "rejected". :) It means "we think we still might want this, but we don't yet have enough information to ensure that it will work nicely with the rest of the language". Sometimes this is because of prerequisite implementation work, indeed, but other times it's simply because designing a feature takes time and energy (gated on the language/library teams, in which sense Rust isn't really a pure bazaar at all) and not all features are equally prioritized.

> Pre-MIR, I'm fairly sure the people who would touch the type/lifetime checker could be counted on one hand, and it was borderline obfuscated due to all the pointless type theory thrown around.

Firstly, one of the places where type theory definitely isn't pointless is when implementing a type checker* (of which borrowck counts as well). :P Secondly, the difficulty of contributing to type checkers in general has little to do with implementation and lots to do with the aforementioned type theory. Thirdly, even pre-MIR, the librustc_typeck directory had 105 contributors, and the librustc_borrowck dir had 60 (and that's only counting back to Nov 2014).

Reply on news.ycombinator.com