module Euler145

imports
  Prelude

where

main :: () -> I32
main () = do
  t = new (0 :: W32)
  times (1000000000 :: W32)
    (\i -> when (is_rev i) (inc t))
  assert (@t == 608720)
  putW @t
  0

is_rev x => branch
  (x % 10) == 0 -> False
  | do
    i = new (x + rev x)
    while ((@i > 0) && (is_odd @i)) (i /= 10)
    @i == 0

is_odd x => (x % 2) == 1

rev x => do
  j = new 0
  for x (\i -> i > 0) (\i -> i / 10)
    (\i -> j <- (@j * 10) + (i % 10))
  @j