let numbers = [0,1,2,3]
let increasedNumbers = numbers.map { $0 + 1 }

let sum = numbers.reduce(0) { $0 + $1 }

((a+b) + c) + d == (a + b) + (c+d)  # associative
a+b == b+a                          # commutative

let main (x: []i32) (y: []i32): i32 =
  reduce (+) 0 (map2 (*) x y)