On Wed, 2002-11-13 at 22:43, William Lee Irwin III wrote:
There is a semantic difference here, as the version I posted above takes
files from the command-line, though it does fail to accommodate the
pass-through case, which is handled by: [...]
I need this behavior often enough to justify writing a small module to
provide it:
Full version at http://tea.moertel.com/~thor/ravt/ravt-0.9/GetInput.hs
-- GetInput.hs
-- Tom Moertel [EMAIL PROTECTED]
-- CVS $Id: GetInput.hs,v 1.1 2002/09/09 04:57:23 thor Exp $
-- | This module provides a method of getting input from files named
-- on the command line or, if no files are provided, from standard
-- input. This mimics Perl's default input handling, which is
-- convenient. Also, the module provides versions of the standard
-- 'interact' function that use these input-getting behaviors.
module GetInput ( getInputDefault, getInputFromArgs
, interactDefault, interactFromArgs) where
import Control.Monad (liftM)
import System.Environment (getArgs)
-- | Reads the arguments passed on the command line and then passes
-- them to 'getInputFromArgs' for handling.
getInputDefault :: IO String
getInputDefault = getArgs = getInputFromArgs
-- | Treats the input list as a list of files from which to read
-- input sequentially. If the list is empty, input is read from
-- standard input. If - is passed as a file, it is taken to
-- mean standard input.
getInputFromArgs:: [String] - IO String
getInputFromArgs [] = getContents
getInputFromArgs xs = liftM concat (mapM readFromFile xs)
where
readFromFile -= getContents
readFromFile file = readFile file
-- | Gets input via 'getInputDefault', processes it with the
-- function argument @f@, and then prints the @String@ that
-- @f@ returns.
interactDefault :: (String - String) - IO ()
interactDefault f = getInputDefault = putStrLn . f
-- | Gets input via 'getInputFromArgs', processes it with the
-- function argument @f@, and then prints the @String@ that
-- @f@ returns.
interactFromArgs:: [String] - (String - String) - IO ()
interactFromArgs args f
= getInputFromArgs args = putStrLn . f
___
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