> Sometimes you don’t want libraries, instead you want to implement similar stuff in your own code. That's always the tradeoff, isn't it? You can implement the

> Sometimes you don’t want libraries, instead you want to implement similar stuff in your own code. That's always the tradeoff, isn't it? You can implement the logic yourself, or modify three lines and immediately get parallel evaluation of you loop (add the dependency in Cargo.toml, add an import statement and modify an .iter() call to .par_iter()). > And Rayon uses unsafe to workround the compiler limitation of the safe rust I was talking about. So does the standard library. Using unsafe is not a cheat, it's not a defeat. It is letting the library developer express something that the borrow checker cannot yet comprehend, at the cost of the developer taking responsibility of upholding the language's invariants. Those "safe rust limitations" are the point, not an accident or misfeature. "If we restrict ourselves to handling the 90% most common cases of problems, we can automate the checks and provide an escape hatch for the other 10%" is the unofficial Rust ethos! The alternatives would be to either sacrifice performance in the general case or sacrifice safety in the general case. Btw, the author of rayon is Niko Matsakis. It's not part of stdlib because of many reasons, but the quality of implementation is not one of them.