A Week with Mozilla's Rust

Post by masklinn » Thu, Aug 22, 2013, 7:37 AM UTC

kzrdude wrote: post #39

masklinn wrote: post #21

Earlier quoted context omitted.

> Also, does the compiler complain about my example above being not exhaustive? Yes, although the error message isn't very good: crypto.rs:55:23: 59:5 error: non-exhaustive patterns: true not covered crypto.rs:55 let computed_key = match (key.len() > self.block_size, key.len() self.zero_pad(self.hash(key).digest), crypto.rs:57 (false, true) => self.zero_pad(key), crypto.rs:58 (false, false) => key crypto.rs:59 }; err…

it should be expressed with conditionals anyway. match key.len() { k if k > self.block_size => .. k if k .. k => ... or even match key.cmp(self.block_size) { Equal => .. Greater => .. Less => ...

Post by dbaupp » Thu, Aug 22, 2013, 7:47 AM UTC

anon3132 wrote: post #67

acqq wrote: post #22

Earlier quoted context omitted.

I've took a look on one "real" example, I admit I haven't spent much time with the language, I just want to get the idea looking at the code which really does something, I like that more than starting with boring tutorials: https://github.com/mozilla/rust/blob/master/src/libextra/jso... I know it's the least interesting thing, but for me the simplest rule to recognize Rust vs Go is that at the moment Go has the nice…

~str is mutable. error probably doesn't need a mutable string, though. either it's just an overlooked API (json is an old part of the codebase, doesn't really see a lot of attention) or what pcwalton said about calling something down the line.

Post by dbaupp » Thu, Aug 22, 2013, 8:45 AM UTC

TheZenPsycho wrote: post #63

general_failure wrote: post #60

Why do people keep reinventing syntax? Quick tell me what the following mean: struct Digest { digest: ~[u8] } // what's ~ here? for self.digest.iter().advance |&byte| { acc = acc.append(fmt!("%02x", byte as uint)); } acc What does the above mean? acc as a separate line and nothing else I hate it when people reinvent the same construct that can be found in other languages but differently. I guess they want to do somet…

just offhand, from my understanding, ~ signifies rust's pointer type. It's different from C's pointer type in subtle ways, so the symbol is different, to force reader to actually look into it, and understand what it does different instead of just assuming it's just like C's. There's also the advantage that there's no way to conflict with the * multiplication operator.

  foo * bar = NULL; // C

  let bar: *Foo = std::ptr::null(); // Rust

  let bar = std::ptr::null(); // Rust, using type inference

Post by lucian1900 » Thu, Aug 22, 2013, 9:26 AM UTC

catnaroek wrote: post #25

dkhenry wrote: post #11

Of all the upcoming languages out there. I think rust is best positioned. The fact that it is really the only contender that can preform the same role as C, but it folds in lots of the language design theory of the past three decades puts it in a league of its own.

Exactly! This is what makes Rust exciting - as opposed to yawnfests like Go that merely provide a compiled, somewhat faster Python.

Post by relistan » Thu, Aug 22, 2013, 9:33 AM UTC

kzrdude wrote: post #39

masklinn wrote: post #21

Earlier quoted context omitted.

> Also, does the compiler complain about my example above being not exhaustive? Yes, although the error message isn't very good: crypto.rs:55:23: 59:5 error: non-exhaustive patterns: true not covered crypto.rs:55 let computed_key = match (key.len() > self.block_size, key.len() self.zero_pad(self.hash(key).digest), crypto.rs:57 (false, true) => self.zero_pad(key), crypto.rs:58 (false, false) => key crypto.rs:59 }; err…

it should be expressed with conditionals anyway. match key.len() { k if k > self.block_size => .. k if k .. k => ... or even match key.cmp(self.block_size) { Equal => .. Greater => .. Less => ...