fancier prompts for ghci

It'd be nice to put newlines in a GHCi prompt using standard escape sequences.

It is really unnecessary to support anything more than %s as a formatting directive.

Trac metadata

Trac field	Value
Version	6.8.3
Type	FeatureRequest
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture

changed weight to 5

added Tfeature request Trac import labels

changed milestone to %6.10 branch

Trac metadata

Trac field	Value
Component	Compiler → GHCi

I've integrated this with GHC 6.8.3 sources. There's not much to it.

--- 0/compiler/ghci/InteractiveUI.hs	2008-06-16 10:27:16.000000000 -0700
+++ 1/compiler/ghci/InteractiveUI.hs	2008-10-28 02:57:03.000000000 -0700
@@ -1447,11 +1447,19 @@
 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 }
+      then io $ hPutStrLn stderr $
+        "syntax: :set prompt <prompt>, currently \"" ++ prompt st ++ "\""
+      else setGHCiState st{ prompt = read . handleQuotes $ value }
   where
-     remQuotes ('\"':xs) | not (null xs) && last xs == '\"' = init xs
-     remQuotes x = x
+     -- the prompt can be input with quote marks and string escaping, or
+     -- with plain character escaping.
+     handleQuotes s | length s > 2 && last s == '"' && head s == '"' = s
+                    | otherwise = wrap . escapeQuotes $ s
+     wrap = ("\"" ++) . (++ "\"")
+     escapeQuotes ('\\':'"':r) = '\\' : '"' : escapeQuotes r
+     escapeQuotes ('"':r) = '\\' : '"' : escapeQuotes r
+     escapeQuotes (c:r) = c : escapeQuotes r
+     escapeQuotes [ ] = [ ]
 
 setOptions wds =
    do -- first, deal with the GHCi opts (+s, +t, etc.)

With quotes, it uses string escapes and retains spaces:

Prelude> :set prompt "{-  %s\n -} "
{-  Prelude
 -}  

Without quotes, it uses only character escapes:

Prelude> :set prompt {-\SP\SP%s\n\SP-}\SP
{-  Prelude
 -}  

Attached file rubbish (download).

this is the diff mentioned in comment 3 (turns out the diff is not extractable in this version of trac)

assigned to @trac-igloo

mentioned in commit ff8799ef

closed

Thanks for the patch! I've applied a slightly different version: Prompt strings starting with " are treated as Haskell strings; otherwise they are treated as literal strings.

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedFixed

reopened

Replying to [ticket:2652#comment:29920 igloo]:

Thanks for the patch! I've applied a slightly different version: Prompt strings starting with " are treated as Haskell strings; otherwise they are treated as literal strings.

Is this going to be in 6.12? I've noticed it's not included in 6.10.

Trac metadata

Trac field	Value
Resolution	ResolvedFixed → Unresolved

Yes, this patch is only in the HEAD (which will become 6.12):

Fri Oct 31 14:52:27 GMT 2008  Ian Lynagh <igloo@earth.li>
  * :set prompt now understand Haskell String syntax; trace #2652

closed

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedFixed

added Pnormal label