Rust code shared from the playground

playground.rs

fn main () {
    let number: f64 = 20.;
    // Perform a pipeline of options.
    let result = Some(number)
        .map(inverse) // Described below.
        .map(double)
        .map(inverse)
        .and_then(log) // Described below.
        .map(square)
        .and_then(sqrt);
    // Extract the result.
    match result {
        Some(x) => println!("Result was {}.", x),
        None    => println!("This failed.")
    }
}
// You can ignore these.
fn log(value: f64) -> Option<f64> {
    match value.log2() {
        x if x.is_normal() => Some(x),
        _                  => None
    }
}
fn sqrt(value: f64) -> Option<f64> {
    match value.sqrt() {
        x if x.is_normal() => Some(x),
        _                  => None
    }
}
fn double(value: f64) -> f64 {
    value * 2.
}
fn square(value: f64) -> f64 {
    value.powi(2 as i32)
}
fn inverse(value: f64) -> f64 {
    value * -1.
}