piping

piping provides a pipe! macro that allows you to use the pipeline operator in Rust.

let wrapped = orig_and_double(add(2, num)).1 as isize;

let piped = pipe! {
	num |> add(2, _) |> orig_and_double(_),
	(_, doubled) |> doubled as isize,
};

Features

• Hack-like syntax.
• Multiple pipelines in one statement.
• Destructuring of previous pipeline results.

Docs

Documentation is provided on docs.rs.

How does it work?

fn add(a: usize, b: usize) -> usize {
	a + b
}

fn orig_and_double(num: usize) -> (usize, usize) {
	(num, num * 2)
}

let num = 4;

let piped = pipe! {
	num |> add(2, _) |> orig_and_double(_),
	(_, doubled) |> doubled as isize,
};

// Expands to...
let piped = {
	let __pipeline_value__ = num;
	let __pipeline_value__ = add(2, __pipeline_value__);
	let (_, doubled) = orig_and_double(__pipeline_value__);
	doubled as isize
};

You can pass any expression in as the input.

Notice that you can chain pipelines with ,s to destructure the result of the previous pipeline.

To use _ as it is normally in Rust, use __ instead.

The macro also tries to optimize the generated code to minimize the amount of reassigning done.