On 20 September 2012 22:55, Gregory Collins
consequently, there seems to be no reason to use the word8 library: not only is it not faster, it's actually a pessimization.
When I run the following benchmark: main :: IO () main = do input <- S.readFile "bench.hs" defaultMain [ bench "Word8-local" $ nf (S.length . S.map toLower8) input , bench "Char8 toLowerC" $ nf (S.length . S8.map toLowerC) input ] toLower8 :: Word8 -> Word8 toLower8 w | isUpper8 w = w + 32 | otherwise = w {-# INLINE toLower8 #-} isUpper8 :: Word8 -> Bool isUpper8 w = 0x41 <= w && w <= 0x5a || 0xc0 <= w && w <= 0xd6 || 0xd8 <= w && w <= 0xde {-# INLINE isUpper8 #-} toLowerC :: Char -> Char toLowerC w | isUpperC w = unsafeChr $ ord w + 0x20 | otherwise = w isUpperC :: Char -> Bool isUpperC w = '\x41' <= w && w <= '\x5a' || '\xc0' <= w && w <= '\xd6' || '\xd8' <= w && w <= '\xde' I get the following results: benchmarking Word8-local mean: 8.939985 us, lb 8.921876 us, ub 8.960350 us, ci 0.950 std dev: 97.99953 ns, lb 86.79926 ns, ub 113.6396 ns, ci 0.950 benchmarking Char8 toLowerC mean: 3.468023 us, lb 3.461577 us, ub 3.475718 us, ci 0.950 std dev: 35.93801 ns, lb 30.56892 ns, ub 49.77021 ns, ci 0.950 However when I _remove_ the INLINE pragmas they become equally fast: benchmarking Word8-local mean: 3.563220 us, lb 3.555527 us, ub 3.572971 us, ci 0.950 std dev: 44.12678 ns, lb 36.22663 ns, ub 58.41914 ns, ci 0.950 benchmarking Char8 toLowerC mean: 3.534374 us, lb 3.526955 us, ub 3.542637 us, ci 0.950 std dev: 40.27805 ns, lb 35.64414 ns, ub 46.59990 ns, ci 0.950 Adding an INLINE pragma to toLowerC and isUpperC doesn't change the results. I'm on GHC-7.6.1 using -O2. Bas