Thoughts on Rust, a few thousand lines in

Post by faitswulff » Thu, Jan 10, 2019, 12:52 AM UTC

f2f wrote: post #105

daboross wrote: post #91

Earlier quoted context omitted.

Could you site this? I've looked at ilovecaching's comment history (at least up to ~60 days ago) and they seem consistent on being a networking programmer who uses C++. Was there a particular comment you found which would indicate this isn't the truth?

nb: you mean "cite". why would you make me do this? you can doxx people on your own dime... still, for posterity: https://news.ycombinator.com/item?id=18328964 "...now I am working full time as a Rust developer" https://news.ycombinator.com/item?id=18310666 "As a long time Erlang developer..." https://news.ycombinator.com/item?id=18265199 "As someone who has worked two jobs now writing, deploying, and operating Erlan…

Post by moosingin3space » Thu, Jan 10, 2019, 12:58 AM UTC

estebank wrote: post #110

moosingin3space wrote: post #67

Earlier quoted context omitted.

In Rust, you're supposed to use `unicode-segmentation`[1] if you need to split on logical character (grapheme cluster in the Unicode standard). Otherwise, the iterators `.bytes` emits raw bytes, and `.chars` emits UTF-8 codepoints. Basically, string indexing is a lot harder than it seems at first glance, depending on what you want.

One nitpick: `.chars`[1] gives you an iterable[2] of `char`s[3], each of which is always a 4 byte representation of a valid unicode character. This means that `"asdf".chars().collect()` will have a different size to `"asdf"` and `"asdf".chars().as_str()`. `.chars()` will never give you an incomplete codepoint, but it will give you incomplete characters, as you could have many c̶̼̟̏ó̷̘̉n̴̖̞̏̇t̸̡̃ĭ̸̻̬n̴̯͉̂͑ṵ̴̑a̷̛̫̳t…

Post by int_19h » Thu, Jan 10, 2019, 1:00 AM UTC

cphoover wrote: post #10

I've not done any rust dev before but the whole variable shadowing thing really scares me, in that it makes it not obvious where the initial declaration comes from. This seems difficult to reason about.

Post by int_19h » Thu, Jan 10, 2019, 1:03 AM UTC

StreamBright wrote: post #9

let foo = "..."; let foo = parse(foo); let foo = escaped(foo); Is it really shadowing or mutation of foo? I would consider this shadowing (something you can do in OcaML): let foo = "..." in let foo = parse(foo) in let foo = escaped(foo) in dosomething(foo);;

  let foo = "..." in
  let foo = parse(foo) in
  let foo = escaped(foo) in
  ...

Post by burntsushi » Thu, Jan 10, 2019, 1:15 AM UTC

int_19h wrote: post #103

burntsushi wrote: post #82

Earlier quoted context omitted.

> How often comparatively do you want the nth byte compared to the nth character? I would suspect that's pretty rare. It's exactly the opposite of what you expect. Getting the nth codepoint is often (not always) semantically incorrect since a codepoint isn't necessarily one character. Multiple codepoints might combine to form one character. (In Unicode, these are called grapheme clusters.) Byte offsets are used a ton…

I still think that using the common [] operator for this is a mistake. Strings shouldn't offer [] at all, and instead should provide methods like codepoints(), bytes(), grapheme_clusters() etc for indexing, slicing, and iterating. The reason being that the behavior of [] for string varies widely in different languages, and so this is something that's best made explicit, both to force the author of the code to conside…