pipe_filter.nula

// Pipe & Filter — data transformation pipelines using the `|>` operator
// and closures. Each stage is a pure function that transforms data;
// chaining them builds a readable processing pipeline.
//
// Run with: nulang examples/pipe_filter.nula

// -- Pipeline stages as pure functions --
fn double(n: Int) -> Int { n * 2 }

fn add_ten(n: Int) -> Int { n + 10 }

fn is_even(n: Int) -> Bool { n % 2 == 0 }

// -- String processing pipeline --
fn shout(s: String) -> String { s + "!" }

fn greet(name: String) -> String { "Hello, " + name }

fn main() {
    // Arithmetic pipeline with the pipe operator
    let result = 5
        |> double
        |> add_ten
        |> double
    perform IO.print(perform Int.to_string(result))

    // Boolean pipeline
    let flag = 42
        |> double
        |> is_even
    perform IO.print(if flag then "even" else "odd")

    // String pipeline
    let message = "world"
        |> greet
        |> shout
    perform IO.print(message)

    // Anonymous closure in a pipeline
    let inc = fn(n) { n + 1 }
    let v = 41 |> inc
    perform IO.print(perform Int.to_string(v))

    // Multi-step closure pipeline
    let triple = fn(n) { n * 3 }
    let square = fn(n) { n * n }
    let w = 2 |> triple |> square
    perform IO.print(perform Int.to_string(w))

    0
}