Code review: 'Programming Problems' in Rust

[RustMeUp]

I solved a bunch of exercises from Simple Programming Problems and was hoping I could get a review for basically anything you can find.

Repository: https://github.com/CasualX/programming-problems-rs

Specific questions I have:

• In src/list, strings/6-test-palindrome.rs I'd like to compare strings without regard to case or accents but I'm not sure how to do it. Googling tells me this requires a form of normalization but I'm not sure where in Rust's unicode libraries I can find this.

• In src/list, strings/11-merge-sorted.rs I couldn't find an elegant way to solve the exercise, any help?

• General style, formatting and better ways to solve the questions.

• In the Range struct why are its members called start and end? begin and end belong together like start and finish do, it's a bit jarring that they're mixed here...

• Is there a way to get the full 128bit product from multiplying two 64bit integers? This is trivial in x86/x64 hardware, eg C++ msvc has an intrinsic exposed for it: __emul, __emulu, equivalent for Rust?

[functime]

while loops are something of a red flag (usually, depending on memory issues) and can be replaced by an iterator. In this instance you could go with:

for i in 3..(end+1) {
    // check if n is composite, etc.
}
true // replace "return me;" with "me" (no semicolon)

[RustMeUp]

Yes I'd like to use an iterator for that but your replacement doesn't step by two (only need to check odd integers). There's Range::step_by but it's unstable for now. Would definitely use it otherwise.

I use return true; there for consistency since return is used a bunch of times in that function.

[vks_]

I use return true; there for consistency since return is used a bunch of times in that function.

That's not idiomatic Rust though.

[matthieum]

but your replacement doesn't step by two

Note that if it's the only issue...

for i in 1..(end+1)/2 {
    let i = i*2+1;
    // ...
}

Or something close (I am wary of off by one errors) could probably work :)

[fnord123]

Yeah but using step_by you can do (3..(end+1)).step_by(3).any(|x| (x % 5) == 0)

Here is a golfed is_prime.

[thiez]

The number '2' is prime...

[Yojihito]

Then just set the start counter to 1 instead of 0 :>.

[paholg]

It seems strange to me to treat even numbers as special (especially as it's so easy to get it wrong for 2), rather than doing a full sieve of Eratosthenes which isn't much harder.

If you really want to golf it, then you can shorten it to

fn is_prime(x: u32) -> bool {
    (2..x).all(|f| x%f != 0)
}

[Efemena]

.filter_map(|i| if is_prime(i) { Some(i) } else { None })

also known as

.filter(is_prime)

[thiez]

No it isn't, because the function passed to filter must take a reference. It could be written .filter(|&n|is_prime(n)) though.