[project @ 2005-03-24 16:14:00 by simonmar]

Cleanup the upsweep strategy in GHC.load.

Now it's hopefully clearer how we decide what modules to recompile,
and which are "stable" (not even looked at) during a reload.  See the
comments for details.

Also, I've taken some trouble to explicitly prune out things that
aren't required before a reload, which should reduce the memory
requirements for :reload in GHCi.  Currently I believe it keeps most
of the old program until the reload is complete, now it shouldn't
require any extra memory.

1 files changed, 14 insertions, 1 deletions

diff --git a/ghc/compiler/utils/Util.lhs b/ghc/compiler/utils/Util.lhs
index d51a09d9ab..2f20226794 100644
--- a/ghc/compiler/utils/Util.lhs
+++ b/ghc/compiler/utils/Util.lhs
@@ -56,6 +56,7 @@ module Util (
 	-- IO-ish utilities
 	createDirectoryHierarchy,
 	doesDirNameExist,
+	modificationTimeIfExists,
 
 	later, handleDyn, handle,
 
@@ -89,10 +90,12 @@ import List		( zipWith4 )
 #endif
 
 import Monad		( when )
-import IO		( catch )
+import IO		( catch, isDoesNotExistError )
 import Directory	( doesDirectoryExist, createDirectory )
 import Char		( isUpper, isAlphaNum, isSpace, ord, isDigit )
 import Ratio		( (%) )
+import Time		( ClockTime )
+import Directory	( getModificationTime )
 
 infixr 9 `thenCmp`
 \end{code}
@@ -840,6 +843,16 @@ handle h f = f `Exception.catch` \e -> case e of
 #endif
 
 -- --------------------------------------------------------------
+-- check existence & modification time at the same time
+
+modificationTimeIfExists :: FilePath -> IO (Maybe ClockTime)
+modificationTimeIfExists f = do
+  (do t <- getModificationTime f; return (Just t))
+	`IO.catch` \e -> if isDoesNotExistError e 
+			then return Nothing 
+			else ioError e
+
+-- --------------------------------------------------------------
 -- Filename manipulation
 		
 type Suffix = String