Here's an example:
{-# LANGUAGE MagicHash #-}
import GHC.Prim
import GHC.Types
import Data.Word
main :: IO ()
main = do
let word = 5 :: Word
res =
case word of
W# w -> W# (popCnt64# w)
print res
On Sun, Mar 20, 2016 at 12:19 PM, John Ky
Hello Haskellers,
Does anyone know how to call popCnt64# from the GHC.Prim module?
This was my failed attempt:
λ> popCnt64# 1
<interactive>:14:11: Couldn't match kind ‘*’ with ‘#’ When matching types a0 :: * Word# :: # Expected type: Integer -> Word# Actual type: Integer -> a0 In the first argument of ‘popCnt64#’, namely ‘1’ In the expression: popCnt64# 1 In an equation for ‘it’: it = popCnt64# 1
-John
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