Traits in Rust seem at least superficially similar to typeclasses in Haskell, however I’ve seen people write that there are some differences between them. I was wondering exactly what these differences are. 3 Answers 3
I’m reading the documentation for File: //.. let mut file = File::create(“foo.txt”)?; //.. What is the ? in this line? I do not recall seeing it in the Rust Book before. 3 Answers 3
I wrote some Rust code that takes a &String as an argument: fn awesome_greeting(name: &String) { println!(“Wow, you are awesome, {}!”, name); } I’ve also written code that takes in a reference to a Vec or Box: fn total_price(prices: &Vec<i32>) -> i32 { prices.iter().sum() } fn is_even(value: &Box<i32>) -> bool { **value % 2 == … Read more
I wasn’t able to find the Rust equivalent for the “join” operator over a vector of Strings. I have a Vec<String> and I’d like to join them as a single String: let string_list = vec![“Foo”.to_string(),”Bar”.to_string()]; let joined = something::join(string_list,”-“); assert_eq!(“Foo-Bar”, joined); Related: What’s an idiomatic way to print an iterator separated by spaces in Rust? … Read more
How do you access a Cargo package’s metadata (e.g. version) from the Rust code in the package? In my case, I am building a command line tool that I’d like to have a standard –version flag, and I’d like the implementation to read the version of the package from Cargo.toml so I don’t have to … Read more
With Rust being comparatively new, I’ve seen far too many ways of reading and writing files. Many are extremely messy snippets someone came up with for their blog, and 99% of the examples I’ve found (even on Stack Overflow) are from unstable builds that no longer work. Now that Rust is stable, what is a … Read more
By following this guide I created a Cargo project. src/main.rs fn main() { hello::print_hello(); } mod hello { pub fn print_hello() { println!(“Hello, world!”); } } which I run using cargo build && cargo run and it compiles without errors. Now I’m trying to split the main module in two but cannot figure out how … Read more
What is the best way to create and use a struct with only one instantiation in the system? Yes, this is necessary, it is the OpenGL subsystem, and making multiple copies of this and passing it around everywhere would add confusion, rather than relieve it. The singleton needs to be as efficient as possible. It … Read more
I’m having a hard time figuring out how string syntax works in Rust. Specifically, I’m trying to figure out how to make a multiple line string. 5 Answers 5
When running a sum loop over an array in Rust, I noticed a huge performance drop when CAPACITY >= 240. CAPACITY = 239 is about 80 times faster. Is there special compilation optimization Rust is doing for “short” arrays? Compiled with rustc -C opt-level=3. use std::time::Instant; const CAPACITY: usize = 240; const IN_LOOPS: usize = … Read more
