module General.Extra(
getProcessorCount,
randomElem,
showQuote,
withs,
) where
import Control.Exception.Extra
import Data.Char
import Data.List
import System.Environment.Extra
import System.IO.Extra
import System.IO.Unsafe
import System.Random
#if __GLASGOW_HASKELL__ >= 704
import Control.Concurrent
import Foreign.C.Types
#endif
showQuote :: String -> String
showQuote xs | any isSpace xs = "\"" ++ concatMap (\x -> if x == '\"' then "\"\"" else [x]) xs ++ "\""
| otherwise = xs
#if __GLASGOW_HASKELL__ >= 704
foreign import ccall getNumberOfProcessors :: IO CInt
#endif
getProcessorCount :: IO Int
getProcessorCount = let res = unsafePerformIO act in return res
where
act =
#if __GLASGOW_HASKELL__ >= 704
if rtsSupportsBoundThreads then
fmap fromIntegral $ getNumberOfProcessors
else
#endif
handle_ (const $ return 1) $ do
env <- lookupEnv "NUMBER_OF_PROCESSORS"
case env of
Just s | [(i,"")] <- reads s -> return i
_ -> do
src <- readFile' "/proc/cpuinfo"
return $! length [() | x <- lines src, "processor" `isPrefixOf` x]
randomElem :: [a] -> IO a
randomElem xs = do
i <- randomRIO (0, length xs 1)
return $ xs !! i
withs :: [(a -> r) -> r] -> ([a] -> r) -> r
withs [] act = act []
withs (f:fs) act = f $ \a -> withs fs $ \as -> act $ a:as