Own-Programming-Language-Tutorial/examples/functions/stream.own

use ["std", "functional"]

println "x, square(x), cube(x) for even numbers"
data = [1,2,3,4,5,6,7,8,9]
stream(data)
  .filter(def(x) = x % 2 == 0)
  .map(def(x) = [x, x * x, x * x * x])
  .sortBy(def(x) = -x[2])
  .forEach(::echo)


println "\nReverse custom operator"
data = [2, 4, 6, 5, 12, 34, 0, 18]
rev = stream(data).custom(::reverse).toArray()
println data
println rev

def reverse(container) {
  size = length(container)
  result = newarray(size)
  for i : range(size) {
    result[size - i - 1] = container[i]
  }
  return result
}