Tour of Lux · chapter 3 of 8

Functions & pipes

Definitions, lambdas, and the pipe operator.

Functions declare parameter and return types with : and ->. The last expression of a block is its value — no return needed (though it exists).

fn fib(n: int) -> int:
    if n <= 1:
        n
    else:
        fib(n - 1) + fib(n - 2)

fn main():
    println("fib(20) = {fib(20)}")

Lambdas are written x -> x + 1. The pipe operator |> feeds a value into the next call, so transformations read left to right. Builtins like map, filter, and sum also work method-style.

fn main():
    let result = [1, 2, 3, 4, 5, 6, 7, 8]
        |> filter(x -> x % 2 == 0)
        |> map(x -> x * x)
        |> sum()
    println("sum of squared evens: {result}")

    println([5, 3, 8, 1].sort())

← Values Control flow →