4 ms·

See the lent annotation? No copying involved. Its a hidden pointer. https://nim-lang.github.io/Nim/options.html#get%2COption%5BT%5D https://nim-lang.github.io/

• jlokier 5y ago
  It's a great idea. I really like a lot of Nim's language design, including from a performance perspectice. If only things were implemented as reliably and nicely as the design suggests. I think people like the neat documented language and take for granted that the implementation must have all things that are implied or suggested by the design, when it's not quite up to natural expectations in practice: > @mratsim: As a potential impact, I tried to use options in my RayTracer, but they were 5x slower (not just a couple dozen percents like the iterator issue in #14421) than passing mutable parameter + bool > @araq: Well nobody claimed Option[T] is a lightweight abstraction. > @mratsim: I was misled by Rust code :/ https://github.com/nim-lang/Nim/issues/14420#issuecomment-632886274 https://github.com/nim-lang/Nim/issues/14420#issuecomment-63... Without going into details of any particular problem, I can safely say that when I profile Nim code at runtime, I see a lot more copying than I think was intended by authors. And when I look at the generated C code, I see a lot of temporary objects and redundant copies into and out of them, where it's obvious just from reading a few lines in the C code they are redundant. Not just copies that could be cleverly turned into pointers by lent etc., but temporaries that trivially don't need to be there even without fancy lent/borrowing optimisations.
  • planetis 5y ago
    > And when I look at the generated C code, I see a lot of temporary objects yea it sucks, hopefully it would be fixed soon. https://github.com/nim-lang/Nim/issues/18341 https://github.com/nim-lang/Nim/issues/18341