vec-utils

This is an experimental crate that adds some helpful functionality to Vec<T>, like map and zip_with. These functions allow you to transform a vec and try and reuse the allocation if possible!

use vec_utils::VecExt;

fn to_bits(v: Vec<f32>) -> Vec<u32> {
    v.map(|x| x.to_bits())
}

fn sum_2(v: Vec<f32>, w: Vec<f64>) -> Vec<f64> {
    v.zip_with(w, |x, y| f64::from(x) + y)
}

But zip_with is limited to taking only a single additional vector. To get around this limitation, this crate also exports some macros that can take an arbitrary number of input vectors, and in most cases will compile down to the same assembly as Vec::map and Vec::zip_with (sometimes with some additional cleanup code, but even then the macro solution is just as fast as the built-in version).

You can use the zip_with and try_zip_with macros like so,

use vec_utils::{zip_with, try_zip_with};

fn to_bits(v: Vec<f32>) -> Vec<u32> {
    zip_with!(v, |x| x.to_bits())
}

fn sum_2(v: Vec<f32>, w: Vec<f64>) -> Vec<f64> {
    zip_with!((v, w), |x, y| f64::from(x) + y)
}

fn sum_5(a: Vec<i32>, b: Vec<i32>, c: Vec<i32>, d: Vec<i32>, e: Vec<i32>) -> Vec<i32> {
    zip_with!((a, b, c, d, e), |a, b, c, d, e| a + b + c + d + e)
}

fn mul_with(a: Vec<i32>) -> Vec<i32> {
    zip_with!((a, vec![0, 1, 2, 3, 4, 5, 6, 7]), |a, x| a * x)
}

fn to_bits_no_nans(v: Vec<f32>) -> Result<Vec<u32>, &'static str> {
    try_zip_with!(v, |x| if x.is_nan() { Err("Found NaN!") } else { Ok(x.to_bits()) })
}

You can use as many input vectors as you want, just put them all inside the input tuple. Note that the second argument is not a closure, but syntax that looks like a closure, i.e. you can't make a closure before-hand and pass it as the second argument. Also, you can't use general patterns in the "closure"'s arguments, only identifiers are allowed. You can specify if you want a move closure by adding the move keyword in from of the "closure".

use vec_utils::zip_with;

fn add(a: Vec<i32>, b: i32) -> Vec<i32> {
    zip_with!(a, move |a| a + b)
}

It also adds some functionality to reuse the allocation of a Box<T>, using the BoxExt/UninitBox api.

use vec_utils::BoxExt;

fn replace(b: Box<i32>, f: f32) -> Box<f32> {
    Box::drop_box(b).init(f)
}

fn get_and_replace(b: Box<i32>, f: f32) -> (Box<f32>, i32) {
    let (b, x) = Box::take_box(b);
    (b.init(f), x)
}