> the branch may or may not be optimized out That's true, and while I agree that it is a concern, is there ever a way to gain both ergonomics and optimization?

> the branch may or may not be optimized out That's true, and while I agree that it is a concern, is there ever a way to gain both ergonomics and optimization? In other words, aren't we always leaving it up to the compiler one way or another? You mention C++'s specialization, and I suppose that is a solution, but then you are (potentially, I can't say for certain) sacrificing compile times. Although I will admit that this is probably a fair trade for certainty of optimization, and it would be nice if Rust at least offered some amount of specializing. > you really do have to babysit Rust to get efficient codegen. https://rust.godbolt.org/z/PjW5vo https://rust.godbolt.org/z/PjW5vo Oh wow, that is interesting. Yeah, that probably speaks to Rust still being a relatively new language, although I would have expected LLVM to do something about that... In any case, that's certainly no zero-cost abstraction. Thanks for the neat info!