A rich user interface for line input in command-line programs. Haskeline is Unicode-aware and runs both on POSIX-compatible systems and on Windows.

Users may customize the interface with a ~/.haskeline file; see the System.Console.Haskeline.Prefs module for more details.

An example use of this library for a simple read-eval-print loop is the following:

 import System.Console.Haskeline
 
 main :: IO ()
 main = runInputT defaultSettings loop
    where 
        loop :: InputT IO ()
        loop = do
            minput <- getInputLine "% "
            case minput of
                Nothing -> return ()
                Just "quit" -> return ()
                Just input -> do outputStrLn $ "Input was: " ++ input
                                 loop

If either stdin or stdout is not connected to a terminal (for example, piped from another process), Haskeline will treat it as a UTF-8-encoded file handle.

A useful default. In particular:

 defaultSettings = Settings {
           complete = completeFilename,
           historyFile = Nothing,
           }

The following functions provide portable handling of Ctrl-C events.

These functions are not necessary on GHC version 6.10 or later, which processes Ctrl-C events as exceptions by default.