Does Rust have an equivalent to Python's list comprehension syntax?

Question

Python list comprehension is really simple:

>>> l = [x for x in range(1, 10) if x % 2 == 0]
>>> [2, 4, 6, 8] 

Does Rust have an equivalent syntax like:

let vector = vec![x for x in (1..10) if x % 2 == 0]
// [2, 4, 6, 8]

Answer 1

You can just use iterators:

fn main() {
    let v1 = (0u32..9).filter(|x| x % 2 == 0).map(|x| x.pow(2)).collect::<Vec<_>>();
    let v2 = (1..10).filter(|x| x % 2 == 0).collect::<Vec<u32>>();

    println!("{:?}", v1); // [0, 4, 16, 36, 64]
    println!("{:?}", v2); // [2, 4, 6, 8]
}

Answer 2

cute is a macro for Python-esque list and dictionary (HashMap) comprehensions in Rust.

use cute::c;

let vector = c![x, for x in 1..10, if x % 2 == 0];

Answer 3

For anyone else looking for a python-like list\dict comprehension:

list_comprehension_macro

Python:

even_squares = [x for x in range(1, 10) if x % 2 == 0]

Rust equivalent:

let even_squares = comp![x for x in (1..10) if x % 2 == 0]

Full example

In cargo.toml:

list_comprehension_macro = "*"

Then:

use list_comprehension_macro::comp;
fn main() {
    let arr: Vec<u32> = vec![1, 2, 3, 4];
    let result = comp![x * 2 for x in arr];
}

Answer 4

Since rust 2018, you can do:

use cute::c;
…

let vector = c![x, for x in 1..10, if x % 2 == 0];

see https://doc.rust-lang.org/edition-guide/rust-2018/path-changes.html for why.