primes numbers, effective algorithm

primeS.hs

-- source: http://www.garrisonjensen.com/2015/05/13/haskell-programs-are-lies.html

import qualified Data.Set as PQ

primes :: [Integer]
primes = 2:sieve [3,5..]
  where
    sieve (x:xs) = x : sieve' xs (insertprime x xs PQ.empty)

    sieve' (x:xs) table
        | nextComposite == x = sieve' xs (adjust x table)
        | otherwise          = x : sieve' xs (insertprime x xs table)
      where 
        (nextComposite,_) = PQ.findMin table

    adjust x table
        | n == x    = adjust x (PQ.insert (n', ns) newPQ)
        | otherwise = table
      where
        Just ((n, n':ns), newPQ) = PQ.minView table

    insertprime p xs = PQ.insert (p*p, map (*p) xs)