haskell/Readline.hs

   1 module Readline
   2 ( readline, load_history )
   3 where
   4
   5 -- Pick one of these:
   6 -- GPL license
   7 import qualified System.Console.Readline as RL
   8 -- BSD license
   9 --import qualified System.Console.Editline.Readline as RL
  10
  11 import Control.Monad (when)
  12 import System.Directory (getHomeDirectory, doesFileExist)
  13
  14 import System.IO (hGetLine, hFlush, hIsEOF, stdin, stdout)
  15 import System.IO.Error (tryIOError)
  16
  17 history_file = do
  18     home <- getHomeDirectory
  19     return $ home ++ "/.mal-history"
  20
  21 load_history = do
  22     hfile <- history_file
  23     fileExists <- doesFileExist hfile
  24     when fileExists $ do
  25         content <- readFile hfile
  26         mapM RL.addHistory (lines content)
  27         return ()
  28     return ()
  29
  30 readline prompt = do
  31     hfile <- history_file
  32     maybeLine <- RL.readline prompt
  33     case maybeLine of
  34          Just line -> do
  35              RL.addHistory line
  36              res <- tryIOError (appendFile hfile (line ++ "\n"))
  37              return maybeLine
  38          _ -> return maybeLine