From 2f3a4395da6771abe46d45d48694c3c82f72ad7c Mon Sep 17 00:00:00 2001
From: Simon Marlow <simonmar@microsoft.com>
Date: Wed, 12 Mar 2008 21:57:24 +0000
Subject: [PATCH] #2050: save the GHCi history in ~/.ghc/ghci_history Modified
 version of Judah's patch

---
 compiler/ghci/InteractiveUI.hs |   24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/compiler/ghci/InteractiveUI.hs b/compiler/ghci/InteractiveUI.hs
index 8ff83f9..8b1566a 100644
--- a/compiler/ghci/InteractiveUI.hs
+++ b/compiler/ghci/InteractiveUI.hs
@@ -316,6 +316,11 @@ interactiveUI session srcs maybe_exprs = do
         is_tty <- hIsTerminalDevice stdin
         when is_tty $ do
             Readline.initialize
+
+            withGhcAppData
+                 (\dir -> Readline.readHistory (dir </> "ghci_history"))
+                 (return True)
+            
             Readline.setAttemptedCompletionFunction (Just completeWord)
             --Readline.parseAndBind "set show-all-if-ambiguous 1"
 
@@ -349,11 +354,22 @@ interactiveUI session srcs maybe_exprs = do
                  }
 
 #ifdef USE_READLINE
+   Readline.stifleHistory 100
+   withGhcAppData (\dir -> Readline.writeHistory (dir </> "ghci_history"))
+                  (return True)
    Readline.resetTerminal Nothing
 #endif
 
    return ()
 
+withGhcAppData :: (FilePath -> IO a) -> IO a -> IO a
+withGhcAppData right left = do
+   either_dir <- IO.try (getAppUserDataDirectory "ghc")
+   case either_dir of
+      Right dir -> right dir
+      _ -> left
+
+
 runGHCi :: [(FilePath, Maybe Phase)] -> Maybe [String] -> GHCi ()
 runGHCi paths maybe_exprs = do
   let 
@@ -361,11 +377,9 @@ runGHCi paths maybe_exprs = do
 
    current_dir = return (Just ".ghci")
 
-   app_user_dir = do
-    either_dir <- io $ IO.try (getAppUserDataDirectory "ghc")
-    case either_dir of
-      Right dir -> return (Just (dir </> "ghci.conf"))
-      _ -> return Nothing
+   app_user_dir = io $ withGhcAppData 
+                    (\dir -> return (Just (dir </> "ghci.conf")))
+                    (return Nothing)
 
    home_dir = do
     either_dir <- io $ IO.try (getEnv "HOME")
-- 
1.7.10.4