file copy

copy.hs

module Main where

import System.Environment (getArgs)
import System.IO (withFile, Handle, IOMode(ReadMode, WriteMode))
import Data.ByteString as BS


blockSize :: Int 
blockSize = 32 * 1024

streamCopy :: Handle -> Handle -> IO ()
streamCopy from to = go where 
  go = do
    buffer <- hGet from blockSize
    if BS.length buffer > 0 
      then do 
        hPut to buffer
        go
      else
        return ()

main = do
  [fromPth, toPth] <- getArgs
  withFile fromPth ReadMode $ \fromH ->
    withFile toPth WriteMode $ \toH ->
      streamCopy fromH toH