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authorDon Stewart <dons@cse.unsw.edu.au>2007-03-08 13:07:53 +0100
committerDon Stewart <dons@cse.unsw.edu.au>2007-03-08 13:07:53 +0100
commitfbae7e44a693103919fb2393016249dc059eef16 (patch)
tree761f162516935138fca79cfc826a7a9b253b247b /WMonad.hs
parent4aa9591695e800730109aba87ca84e49dfc4e334 (diff)
downloadmetatile-fbae7e44a693103919fb2393016249dc059eef16.tar
metatile-fbae7e44a693103919fb2393016249dc059eef16.zip
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darcs-hash:20070308120753-9c5c1-89f1c06d6a8f0425701139fe426f08e1cdda42a3
Diffstat (limited to 'WMonad.hs')
-rw-r--r--WMonad.hs7
1 files changed, 4 insertions, 3 deletions
diff --git a/WMonad.hs b/WMonad.hs
index 0c4f913..2851da2 100644
--- a/WMonad.hs
+++ b/WMonad.hs
@@ -67,14 +67,15 @@ trace msg = io $ do
hPutStrLn stderr msg
hFlush stderr
--- | Modify the workspace list
+-- | Modify the workspace list.
modifyWorkspace :: (WorkSpace -> WorkSpace) -> W ()
modifyWorkspace f = do
modify $ \s -> s { workspace = f (workspace s) }
ws <- gets workspace
- trace (show $ ws)
+ trace (show ws) -- log state changes to stderr
--- | Like 'when' but for (WorkSpace -> Maybe a)
+-- | Run a side effecting action with the current workspace. Like 'when' but
+-- for (WorkSpace -> Maybe a).
whenJust :: (WorkSpace -> Maybe a) -> (a -> W ()) -> W ()
whenJust mg f = do
ws <- gets workspace