1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
|
-- A non-copying cp based on mmap.
import System.IO.Posix.MMap
import Control.Monad
import System.Mem
import qualified Data.ByteString as S
import Text.Printf
import Control.Exception
import System.CPUTime
main = do
--should run in constant space, and be faster:
time $ forM_ [0..1000] $ \_ -> do
unsafeMMapFile "/usr/share/dict/words"
putStrLn "\nShould be faster than:\n"
--should run in constant space:
time $ forM_ [0..1000] $ \_ -> do
S.readFile "/usr/share/dict/words"
time :: IO t -> IO t
time a = do
start <- getCPUTime
v <- a
v `seq` return ()
end <- getCPUTime
let diff = (fromIntegral (end - start)) / (10^12)
printf "Computation time: %0.3f sec\n" (diff :: Double)
return v
|
