module Compat
  ( unsafeIOToST
  , uncons
  , packCStringLen
  , unsafeUseAsCStringLen
  , popCount
  ) where

import Control.Monad.ST (unsafeIOToST)
import Data.ByteString (uncons, packCStringLen)
import Data.ByteString.Unsafe (unsafeUseAsCStringLen)
import Data.Bits ((.&.), shiftR)

popCount :: Word64 -> Int
popCount = fromIntegral . sum . map (.&. 1) . take 64 . iterate (`shiftR` 1)