Corecursive primes

primes.coffee

divisor = (x) ->
  c = 0
  r = Math.sqrt(x)
  p = primes(c)
  while p <= r
    return p if x % p == 0
    p = primes(++c)
  x

isPrime = (x) -> divisor(x) == x

divisors = (x) ->
  r = []
  while x > 1
    d = divisor(x)
    r.push d
    x = x/d
  r

primes = (->
  store = [2]
  (x) ->
    while x >= store.length
      next = store[store.length-1] + 1
      until isPrime next
        next++
      store.push next
    store[x]
)()

show = (x) ->
  console.log x, divisors x

show 1007
show 1009
show 2048
show 2049