Modules

use billing.invoice

fn main() {
    const inv = invoice.create(7, 123)
    print("invoice {inv.id}: {inv.total}")
}

pub type Invoice {
    pub id: Int
    pub total: Int
    note: String
}

pub fn create(id: Int, total: Int) -> Invoice {
    Invoice(id: id, total: round_up(total), note: "made by billing")
}

fn round_up(x: Int) -> Int {
    (x + 9) / 10 * 10
}

invoice 7: 130

• src/billing/invoice.kav is the module billing.invoice: the path is the name, so you always know which file a name comes from.
• use billing.invoice brings it in; then invoice.create(…) calls its pub function.
• Everything is private until marked pub, fields included.

Private by default means you can change a module's inside freely: nothing outside can depend on what it doesn't make pub.