Error Handling

Ferret uses explicit error unions (E!T) instead of implicit exceptions.

type Io error {
    denied
}

fn load(ok: bool) -> Io!i32 {
    if ok {
        return 1
    }
    return Io::denied
}

fn read_with_fallback(ok: bool) -> i32 {
    return load(ok) catch -1
}

Handler form:

let value = load(false) catch |err| {
    println(err)
    0
}