Fragile Argument Filter

module Main where

import Data.List

import System.Environment
import System.Directory
import System.Process

getFirstPathArg :: [String] -> String
getFirstPathArg []          =  error "No Path Found"
getFirstPathArg (arg : rest)
    | not $ isPrefixOf "+" arg   = arg
    | otherwise             = getFirstPathArg rest

main = do
    let notepadDir = "C:/Program Files (x86)/Notepad++/notepad++.exe"

    args <- getArgs
    let fileName = getFirstPathArg args

    curDir <- getCurrentDirectory

    runProcess
        notepadDir
        [fileName]
        (Just curDir)
        Nothing
        Nothing
        Nothing
        Nothing

    return ()