medium.learning_rust.function_as_data_type..rs

fn plus_one(a: i32) -> i32 {
    a + 1
}

let b = plus_one;
let c = b(5); //6

let b: fn(i32) -> i32 = plus_one; //same, with type inference
let c = b(5); //6

let b = plus_one;
fn plus_two(b: fn(i32) -> i32, x: i32) -> i32 {
    b(b(x))
}
println!("{}", plus_two(b, 2)); //4