Added option to disable readline.

src/GF/System/Readline.hs

@@ -0,0 +1,51 @@
+{-# OPTIONS -cpp #-}
+
+----------------------------------------------------------------------
+-- |
+-- Module      : GF.System.Readline
+-- Maintainer  : BB
+-- Stability   : (stable)
+-- Portability : (portable)
+--
+-- > CVS $Date: 2005/05/10 14:55:01 $ 
+-- > CVS $Author: bringert $
+-- > CVS $Revision: 1.1 $
+--
+-- Uses the right readline library to read user input.
+-----------------------------------------------------------------------------
+
+module GF.System.Readline (fetchCommand) where
+
+#ifdef USE_READLINE
+
+import System.Console.Readline (readline, addHistory)
+
+#else
+
+import System.IO.Error (try)
+import System.IO (stdout,hFlush)
+
+#endif
+
+#ifdef USE_READLINE
+
+fetchCommand :: String -> IO (String)
+fetchCommand s = do
+  res <- readline s
+  case res of
+   Nothing -> return "q"
+   Just s -> do addHistory s
+                return s
+
+#else
+
+fetchCommand :: String -> IO (String)
+fetchCommand s = do
+  putStr s
+  hFlush stdout
+  res <- try getLine
+  case res of
+   Left e -> return "q"
+   Right l -> return l
+
+#endif