Euler10.pec

module Euler10

// The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.
// Find the sum of all the primes below two million.

imports
  Prelude
  Data.Stack

where

main :: () -> I32
main () = do
  p = new (stack #200000)
  assert (primes 2000000 p)
//  put putW p
  t = sum p
// BAL: printing of W64 is broken  putW t
  assert (t == 142913828922)
  0

sum :: Ptr (Stack #cnt W32) -> W64
sum => fold my_add 0

my_add :: W64 -> W32 -> W64
my_add x y => x + unsafe_cast y // BAL: casting from W32 to W64 isn't unsafe

primes :: W32 -> Ptr (Stack #cnt W32) -> Bool
primes w p => do
  empty p
  b = new (push 2 p)
  for 3 (\i -> @b && (i < w)) (add 2)
    (\i -> when (not (any (is_factor i) p)) (b <- push i p))
  @b

is_factor :: { Arith a, Eq a } => a -> a -> Bool
is_factor x y => (x % y) == 0