project_euler1.ct

alias string = [int];
extern printstr: fn(string): unit;
extern printint: fn(int): unit;

let sum_to = fn(a: int): int {
    let ugly_hack = a + 1;
    let num = a * ugly_hack;
    num/2
};

let three_five_sum = fn(a: int): int {
    let a = a - 1;

    sum_to(a/3) * 3 + sum_to(a/5) * 5 - sum_to(a/15) * 15
};

let main = fn() {
    printstr("result: ");
    printint(three_five_sum(1000))
};