From ff8799ef2c8d0ab976fa9fc00fc4bc94e1ca5af9 Mon Sep 17 00:00:00 2001
From: Ian Lynagh <igloo@earth.li>
Date: Fri, 31 Oct 2008 14:52:27 +0000
Subject: [PATCH] :set prompt now understand Haskell String syntax; trace
 #2652

---
 compiler/ghci/InteractiveUI.hs |   11 +++++++----
 docs/users_guide/ghci.xml      |    4 +++-
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/compiler/ghci/InteractiveUI.hs b/compiler/ghci/InteractiveUI.hs
index 268f05e..4db8900 100644
--- a/compiler/ghci/InteractiveUI.hs
+++ b/compiler/ghci/InteractiveUI.hs
@@ -1499,10 +1499,13 @@ setPrompt value = do
   st <- getGHCiState
   if null value
       then io $ hPutStrLn stderr $ "syntax: :set prompt <prompt>, currently \"" ++ prompt st ++ "\""
-      else setGHCiState st{ prompt = remQuotes value }
-  where
-     remQuotes ('\"':xs) | not (null xs) && last xs == '\"' = init xs
-     remQuotes x = x
+      else case value of
+           '\"' : _ -> case reads value of
+                       [(value', xs)] | all isSpace xs ->
+                           setGHCiState (st { prompt = value' })
+                       _ ->
+                           io $ hPutStrLn stderr "Can't parse prompt string. Use Haskell syntax."
+           _ -> setGHCiState (st { prompt = value })
 
 setOptions wds =
    do -- first, deal with the GHCi opts (+s, +t, etc.)
diff --git a/docs/users_guide/ghci.xml b/docs/users_guide/ghci.xml
index 402c7cb..d929548 100644
--- a/docs/users_guide/ghci.xml
+++ b/docs/users_guide/ghci.xml
@@ -2386,7 +2386,9 @@ bar
 	  Inside <replaceable>prompt</replaceable>, the sequence
 	  <literal>%s</literal> is replaced by the names of the
 	  modules currently in scope, and <literal>%%</literal> is
-	  replaced by <literal>%</literal>.</para>
+	  replaced by <literal>%</literal>. If <replaceable>prompt</replaceable>
+      starts with &quot; then it is parsed as a Haskell String;
+      otherwise it is treated as a literal string.</para>
         </listitem>
       </varlistentry>
 
-- 
1.7.10.4