got rid of almost all 'return ()'

Annex.hs

@@ -61,7 +61,6 @@ gitRepoChange :: Git.Repo -> Annex ()
 gitRepoChange r = do
 	state <- get
 	put state { Internals.repo = r }
-	return ()
 
 {- Returns the backends being used. -}
 backends :: Annex [Backend]
@@ -74,7 +73,6 @@ backendsChange :: [Backend] -> Annex ()
 backendsChange b = do
 	state <- get
 	put state { Internals.backends = b }
-	return ()
 
 {- Returns the full list of supported backends. -}
 supportedBackends :: Annex [Backend]
@@ -95,7 +93,6 @@ flagChange :: FlagName -> Flag -> Annex ()
 flagChange name val = do
 	state <- get
 	put state { Internals.flags = M.insert name val $ Internals.flags state }
-	return ()
 
 {- Gets the value of a String flag (or "" if there is no such String flag) -}
 flagGet :: FlagName -> Annex String

Backend/File.hs

@@ -129,7 +129,7 @@ checkRemoveKey key = do
 				"Could only verify the existence of " ++
 				(show have) ++ " out of " ++ (show need) ++ 
 				" necessary copies"
-			if (not $ null bad) then showTriedRemotes bad else return ()
+			showTriedRemotes bad
 			showLocations key
 			hint
 			return False
@@ -146,7 +146,8 @@ showLocations key = do
 	if (null uuidsf)
 		then showLongNote $ "No other repository is known to contain the file."
 		else showLongNote $ "Try making some of these repositories available:\n" ++ ppuuids
-		
+	
+showTriedRemotes [] = return ()	
 showTriedRemotes remotes =
 	showLongNote $ "I was unable to access these remotes: " ++
 		(Remotes.list remotes)

Commands.hs

@@ -14,6 +14,7 @@ import System.Directory
 import System.Path
 import Data.String.Utils
 import Control.Monad (filterM)
+import Monad (when)
 import List
 import IO
 
@@ -326,9 +327,7 @@ dropKeyCleanup key = do
 setKeyStart :: FilePath -> Annex (Maybe SubCmdPerform)
 setKeyStart tmpfile = do
 	keyname <- Annex.flagGet "key"
-	if (null keyname)
-		then error "please specify the key with --key"
-		else return ()
+	when (null keyname) $ error "please specify the key with --key"
 	backends <- Backend.list
 	let key = genKey (backends !! 0) keyname
 	return $ Just $ setKeyPerform tmpfile key
@@ -392,9 +391,7 @@ initCleanup = do
 fromKeyStart :: FilePath -> Annex (Maybe SubCmdPerform)
 fromKeyStart file = do
 	keyname <- Annex.flagGet "key"
-	if (null keyname)
-		then error "please specify the key with --key"
-		else return ()
+	when (null keyname) $ error "please specify the key with --key"
 	backends <- Backend.list
 	let key = genKey (backends !! 0) keyname
 

Core.hs

@@ -13,6 +13,7 @@ import System.Directory
 import Control.Monad.State (liftIO)
 import System.Path
 import Data.String.Utils
+import Monad (when, unless)
 
 import Types
 import Locations
@@ -37,19 +38,15 @@ shutdown = do
 
 	-- Runs all queued git commands.
 	q <- Annex.queueGet
-	if (q == GitQueue.empty)
-		then return ()
-		else do
-			verbose $ liftIO $ putStrLn "Recording state in git..."
-			liftIO $ GitQueue.run g q
+	unless (q == GitQueue.empty) $ do
+		verbose $ liftIO $ putStrLn "Recording state in git..."
+		liftIO $ GitQueue.run g q
 
 	-- clean up any files left in the temp directory, but leave
 	-- the tmp directory itself
 	let tmp = annexTmpLocation g
 	exists <- liftIO $ doesDirectoryExist tmp
-	if (exists)
-		then liftIO $ removeDirectoryRecursive $ tmp
-		else return ()
+	when (exists) $ liftIO $ removeDirectoryRecursive $ tmp
 	liftIO $ createDirectoryIfMissing True tmp
 
 	return True
@@ -65,11 +62,9 @@ gitAttributes repo = do
 			commit
 		else do
 			content <- readFile attributes
-			if (all (/= attrLine) (lines content))
-				then do
-					appendFile attributes $ attrLine ++ "\n"
-					commit
-				else return ()
+			when (all (/= attrLine) (lines content)) $ do
+				appendFile attributes $ attrLine ++ "\n"
+				commit
 	where
 		attrLine = stateLoc ++ "*.log merge=union"
 		attributes = Git.attributes repo
@@ -150,7 +145,7 @@ getViaTmp key action = do
 verbose :: Annex () -> Annex ()
 verbose a = do
 	q <- Annex.flagIsSet "quiet"
-	if (q) then return () else a
+	unless q a
 showStart :: String -> String -> Annex ()
 showStart command file = verbose $ do
 	liftIO $ putStr $ command ++ " " ++ file ++ " "

GitQueue.hs

@@ -16,6 +16,7 @@ import qualified Data.Map as M
 import System.IO
 import System.Cmd.Utils
 import Data.String.Utils
+import Monad (unless)
 
 import qualified GitRepo as Git
 
@@ -52,9 +53,7 @@ run repo queue = do
  - Complicated by commandline length limits. -}
 runAction :: Git.Repo -> Action -> [FilePath] -> IO ()
 runAction repo action files = do
-	if (null files)
-		then return ()
-		else runxargs
+	unless (null files) runxargs
 	where
 		runxargs = pOpen WriteToPipe "xargs" 
 			(["-0", "git", subcommand action] ++ (params action))

GitRepo.hs

@@ -191,8 +191,7 @@ gitCommandLine repo params = assertLocal repo $
 {- Runs git in the specified repo. -}
 run :: Repo -> [String] -> IO ()
 run repo params = assertLocal repo $ do
-	r <- safeSystem "git" (gitCommandLine repo params)
-	return ()
+	safeSystem "git" (gitCommandLine repo params)
 
 {- Runs a git subcommand and returns its output. -}
 pipeRead :: Repo -> [String] -> IO String

Remotes.hs

@@ -28,6 +28,7 @@ import System.Directory
 import System.Posix.Directory
 import List
 import Maybe
+import Monad (when, unless)
 
 import Types
 import qualified GitRepo as Git
@@ -65,9 +66,9 @@ keyPossibilities key = do
 			let cheap = filter (not . Git.repoIsUrl) allremotes
 			let expensive = filter Git.repoIsUrl allremotes
 			doexpensive <- filterM cachedUUID expensive
-			if (not $ null doexpensive)
-				then Core.showNote $ "getting UUID for " ++ (list doexpensive) ++ "..."
-				else return ()
+			unless (null doexpensive) $ do
+				Core.showNote $ "getting UUID for " ++
+					(list doexpensive) ++ "..."
 			let todo = cheap ++ doexpensive
 			if (not $ null todo)
 				then do

UUID.hs

@@ -63,10 +63,7 @@ getUUID r = do
 	where
 		uncached r = Git.configGet r "annex.uuid" ""
 		cached r g = Git.configGet g (cachekey r) ""
-		updatecache g r u = do
-			if (g /= r)
-				then setConfig (cachekey r) u
-				else return ()
+		updatecache g r u = when (g /= r) $ setConfig (cachekey r) u
 		cachekey r = "remote." ++ (Git.repoRemoteName r) ++ ".annex-uuid"
 
 {- Make sure that the repo has an annex.uuid setting. -}
@@ -74,11 +71,9 @@ prepUUID :: Annex ()
 prepUUID = do
 	g <- Annex.gitRepo
 	u <- getUUID g
-	if ("" == u)
-		then do
-			uuid <- liftIO $ genUUID
-			setConfig configkey uuid
-		else return ()
+	when ("" == u) $ do
+		uuid <- liftIO $ genUUID
+		setConfig configkey uuid
 
 {- Changes a git config setting in both internal state and .git/config -}
 setConfig :: String -> String -> Annex ()
@@ -88,7 +83,6 @@ setConfig key value = do
 	-- re-read git config and update the repo's state
 	g' <- liftIO $ Git.configRead g
 	Annex.gitRepoChange g'
-	return ()
 
 {- Filters a list of repos to ones that have listed UUIDs. -}
 reposByUUID :: [Git.Repo] -> [UUID] -> Annex [Git.Repo]

git-annex.hs

@@ -8,6 +8,7 @@
 import IO (try)
 import System.IO
 import System.Environment
+import Monad
 
 import qualified Annex
 import Types
@@ -42,12 +43,8 @@ tryRun' state errnum (a:as) = do
 			tryRun' state (errnum + 1) as
 		Right (True,state') -> tryRun' state' errnum as
 		Right (False,state') -> tryRun' state' (errnum + 1) as
-tryRun' state errnum [] = do
-	if (errnum > 0)
-		then error $ (show errnum) ++ " failed"
-		else return ()
+tryRun' state errnum [] =
+	when (errnum > 0) $ error $ (show errnum) ++ " failed"
 
 {- Exception pretty-printing. -}
-showErr e = do
-	hPutStrLn stderr $ "git-annex: " ++ (show e)
-	return ()
+showErr e = hPutStrLn stderr $ "git-annex: " ++ (show e)