euler7.opa

INDEX = 10001

iter numbers = Iter.init(2, function(int elm){ elm + 1 }, function(int elm){ elm > 0 })

function iter remove_multiples(int a, iter seq){
    Iter.filter(function(int elm){ mod(elm, a) != 0 }, seq)
}

function primes_init(iter seq){
    match(seq.next()){

      case {none} : {  next : function () { none } }
      case {some:it} : { next : function () { some((it.f1, primes_init(remove_multiples(it.f1, it.f2)))) } }

    }
}

iter primes = primes_init(numbers)

option number = Iter.skip(INDEX - 1, primes).next()

jlog(Int.to_string(Option.get(number).f1))