{-# LANGUAGE MagicHash #-}

module Example where

import GHC.Exts
import Data.Word
import Data.Bits

utf8LengthByLeader :: Word8 -> Int 
utf8LengthByLeader w = c `xor` I# (c# <=# 0#) 
  where 
    !c@(I# c#) = countLeadingZeros (complement w)