Rust (мова програмування)

fn main() {
    println!("hello, world");
}

// Умовний оператор, що показує можливість неявного повернення значення (implicit return).
// На відміну від C++ і схожих мов, у Rust оператор «if» насправді є виразом, і може повертати значення.
fn recursive_factorial(n: u32) -> u32 {
    if n <= 1 {
        1
    } else {
        n * recursive_factorial(n - 1)
    }
}

fn iterative_factorial(n: u32) -> u32 {
    // Variables are declared with `let`.
    // The `mut` keyword allows these variables to be mutated.
    let mut i = 1u32;
    let mut result = 1u32;
    while i <= n {
        result *= i;
        i += 1;
    }
    return result; // An explicit return, in contrast to the prior function.
}

fn iterator_factorial(n: u32) -> u32 {
    // Iterators have a variety of methods for transformations.
    // |accum, x| defines an anonymous function.
    // Optimizations like inline expansion reduce the range and fold
    // to have performance similar to iterative_factorial.
    (1..n + 1).fold(1, |accum, x| accum * x)
}

fn main() {
    println!("Recursive result: {}", recursive_factorial(10));
    println!("Iterative result: {}", iterative_factorial(10));
    println!("Iterator result: {}", iterator_factorial(10));
}

use IntList::{Node, Empty};

// This program defines a recursive datastructure and implements methods upon it.
// Recursive data structures require a layer of indirection, which is provided here
// by a unique pointer, constructed via the `Box::new` constructor. These are
// analogous to the C++ library type `std::unique_ptr`, though with more static
// safety guarantees.
fn main() {
    let list = IntList::new().prepend(3).prepend(2).prepend(1);
    println!("Sum of all values in the list: {}.", list.sum());
    println!("Sum of all doubled values in the list: {}.", list.multiply_by(2).sum());
}

// `enum` defines a tagged union that may be one of several different kinds of values at runtime.
// The type here will either contain no value, or a value and a pointer to another `IntList`.
enum IntList {
    Node(i32, Box<IntList>),
    Empty
}

// An `impl` block allows methods to be defined on a type.
impl IntList {
    fn new() -> Box<IntList> {
        Box::new(Empty)
    }

    fn prepend(self, value: i32) -> Box<IntList> {
        Box::new(Node(value, Box::new(self)))
    }

    fn sum(&self) -> i32 {
        // `match` expressions are the typical way of employing pattern-matching,
        // and are somewhat analogous to the `switch` statement from C and C++.
        match *self {
            Node(value, ref next) => value + next.sum(),
            Empty => 0
        }
    }

    fn multiply_by(&self, n: i32) -> Box<IntList> {
        match *self {
            Node(value, ref next) => Box::new(Node(value * n, next.multiply_by(n))),
            Empty => Box::new(Empty)
        }
    }
}

#![feature(scoped)]

use std::thread;

// This function creates ten threads that all execute concurrently.
// To verify this, run the program several times and observe the irregular
// order in which each thread's output is printed.
fn main() {
    // This string is immutable, so it can safely be accessed from multiple threads.
    let greeting = "Hello";

    let mut threads = Vec::new();
    // `for` loops work with any type that implements the `Iterator` trait.
    for num in 0..10 {
        threads.push(thread::scoped(move || {
            // `println!` is a macro that statically typechecks a format string.
            // Macros are structural (as in Scheme) rather than textual (as in C).
            println!("{} from thread number {}", greeting, num);
        }));
    }

    // The `threads` `Vec` is destroyed here and scoped thread handles are
    // destroyed after joining.
}