expose Control.Monad.join

I think I've been looking for that function for some time.
Ie, I remember wanting to collapse Just Nothing to Nothing.

Annex/TaggedPush.hs

@@ -30,7 +30,7 @@ import Utility.Base64
  - refs, per git-check-ref-format.
  -}
 toTaggedBranch :: UUID -> Maybe String -> Git.Branch -> Git.Branch
-toTaggedBranch u info b = Git.Ref $ join "/" $ catMaybes
+toTaggedBranch u info b = Git.Ref $ intercalate "/" $ catMaybes
 	[ Just "refs/synced"
 	, Just $ fromUUID u
 	, toB64 <$> info

Assistant/Ssh.hs

@@ -105,11 +105,11 @@ removeAuthorizedKeys rsynconly dir pubkey = do
  - present.
  -}
 addAuthorizedKeysCommand :: Bool -> FilePath -> SshPubKey -> String
-addAuthorizedKeysCommand rsynconly dir pubkey = join "&&"
+addAuthorizedKeysCommand rsynconly dir pubkey = intercalate "&&"
 	[ "mkdir -p ~/.ssh"
-	, join "; "
+	, intercalate "; "
 		[ "if [ ! -e " ++ wrapper ++ " ]"
-		, "then (" ++ join ";" (map echoval script) ++ ") > " ++ wrapper
+		, "then (" ++ intercalate ";" (map echoval script) ++ ") > " ++ wrapper
 		, "fi"
 		]
 	, "chmod 700 " ++ wrapper
@@ -217,7 +217,7 @@ mangleSshHostName :: SshData -> String
 mangleSshHostName sshdata = "git-annex-" ++ T.unpack (sshHostName sshdata)
 	++ "-" ++ filter safe extra
   where
-	extra = join "_" $ map T.unpack $ catMaybes
+	extra = intercalate "_" $ map T.unpack $ catMaybes
 		[ sshUserName sshdata
 		, Just $ sshDirectory sshdata
 		]
@@ -229,7 +229,7 @@ mangleSshHostName sshdata = "git-annex-" ++ T.unpack (sshHostName sshdata)
 {- Extracts the real hostname from a mangled ssh hostname. -}
 unMangleSshHostName :: String -> String
 unMangleSshHostName h = case split "-" h of
-	("git":"annex":rest) -> join "-" (beginning rest)
+	("git":"annex":rest) -> intercalate "-" (beginning rest)
 	_ -> h
 
 {- Does ssh have known_hosts data for a hostname? -}

Assistant/WebApp/Configurators/Ssh.hs

@@ -205,7 +205,7 @@ testServer sshinput@(SshInput { inputHostname = Just hn }) = do
 		, rsyncOnly = status == UsableRsyncServer
 		}
 	probe extraopts = do
-		let remotecommand = shellWrap $ join ";"
+		let remotecommand = shellWrap $ intercalate ";"
 			[ report "loggedin"
 			, checkcommand "git-annex-shell"
 			, checkcommand "rsync"
@@ -287,7 +287,7 @@ makeSsh' rsync setup sshdata keypair =
   where
 	sshhost = genSshHost (sshHostName sshdata) (sshUserName sshdata)
 	remotedir = T.unpack $ sshDirectory sshdata
-	remoteCommand = shellWrap $ join "&&" $ catMaybes
+	remoteCommand = shellWrap $ intercalate "&&" $ catMaybes
 		[ Just $ "mkdir -p " ++ shellEscape remotedir
 		, Just $ "cd " ++ shellEscape remotedir
 		, if rsync then Nothing else Just "if [ ! -d .git ]; then git init --bare --shared; fi"
@@ -353,7 +353,7 @@ makeRsyncNet sshinput reponame setup = do
 	 - one recommended by rsync.net documentation. I touch the file first
 	 - to not need to use a different method to create it.
 	 -}
-	let remotecommand = join ";"
+	let remotecommand = intercalate ";"
 		[ "mkdir -p .ssh"
 		, "touch .ssh/authorized_keys"
 		, "dd of=.ssh/authorized_keys oflag=append conv=notrunc"

Assistant/XMPP/Git.hs

@@ -97,7 +97,7 @@ xmppPush cid gitpush handledeferred = runPush SendPack cid handledeferred $ do
 	env <- liftIO getEnvironment
 	path <- liftIO getSearchPath
 	let myenv = M.fromList
-		[ ("PATH", join [searchPathSeparator] $ tmpdir:path)
+		[ ("PATH", intercalate [searchPathSeparator] $ tmpdir:path)
 		, (relayIn, show inf)
 		, (relayOut, show outf)
 		, (relayControl, show controlf)

Backend/SHA.hs

@@ -121,7 +121,7 @@ keyValueE size source = keyValue size source >>= maybe (return Nothing) addE
 selectExtension :: FilePath -> String
 selectExtension f
 	| null es = ""
-	| otherwise = join "." ("":es)
+	| otherwise = intercalate "." ("":es)
   where
 	es = filter (not . null) $ reverse $
 		take 2 $ takeWhile shortenough $

Command/AddUrl.hs

@@ -156,7 +156,7 @@ url2file url pathdepth = case pathdepth of
 		| otherwise -> error "bad --pathdepth"
   where
 	fullurl = uriRegName auth ++ uriPath url ++ uriQuery url
-	frombits a = join "/" $ a urlbits
+	frombits a = intercalate "/" $ a urlbits
 	urlbits = map (filesize . escape) $ filter (not . null) $ split "/" fullurl
 	auth = fromMaybe (error $ "bad url " ++ show url) $ uriAuthority url
 	filesize = take 255

Command/InitRemote.hs

@@ -31,7 +31,7 @@ start [] = do
 	error $ "Specify a name for the remote. " ++
 		if null names
 			then ""
-			else "Either a new name, or one of these existing special remotes: " ++ join " " names
+			else "Either a new name, or one of these existing special remotes: " ++ intercalate " " names
 start (name:ws) = do
 	(u, c) <- findByName name
 	let fullconfig = config `M.union` c	

Command/TransferKeys.hs

@@ -95,7 +95,7 @@ runRequests readh writeh a = do
 
 sendRequest :: Transfer -> AssociatedFile -> Handle -> IO ()
 sendRequest t f h = do
-	hPutStr h $ join fieldSep
+	hPutStr h $ intercalate fieldSep
 		[ serialize (transferDirection t)
 		, serialize (transferUUID t)
 		, serialize (transferKey t)

Command/Version.hs

@@ -27,12 +27,10 @@ start = do
 		showPackageVersion
 		putStrLn $ "local repository version: " ++ fromMaybe "unknown" v
 		putStrLn $ "default repository version: " ++ defaultVersion
-		putStrLn $ "supported repository versions: " ++ vs supportedVersions
+		putStrLn $ "supported repository versions: " ++ unwords supportedVersions
-		putStrLn $ "upgrade supported from repository versions: " ++ vs upgradableVersions
+		putStrLn $ "upgrade supported from repository versions: " ++ unwords upgradableVersions
 		putStrLn $ "build flags: " ++ unwords buildFlags
 	stop
-  where
-	vs = join " "
 
 showPackageVersion :: IO ()
 showPackageVersion = putStrLn $ "git-annex version: " ++ SysConfig.packageversion

Common.hs

@@ -2,7 +2,7 @@
 
 module Common (module X) where
 
-import Control.Monad as X hiding (join)
+import Control.Monad as X
 import Control.Monad.IfElse as X
 import Control.Applicative as X
 import "mtl" Control.Monad.State.Strict as X (liftIO)
@@ -10,7 +10,7 @@ import Control.Exception.Extensible as X (IOException)
 
 import Data.Maybe as X
 import Data.List as X hiding (head, tail, init, last)
-import Data.String.Utils as X
+import Data.String.Utils as X hiding (join)
 
 import "MissingH" System.Path as X
 import System.FilePath as X

Git/Construct.hs

@@ -130,7 +130,8 @@ remoteNamed n constructor = do
 remoteNamedFromKey :: String -> IO Repo -> IO Repo
 remoteNamedFromKey k = remoteNamed basename
   where
-	basename = join "." $ reverse $ drop 1 $ reverse $ drop 1 $ split "." k
+	basename = intercalate "." $ 
+		reverse $ drop 1 $ reverse $ drop 1 $ split "." k
 
 {- Constructs a new Repo for one of a Repo's remotes using a given
  - location (ie, an url). -}

Git/Queue.hs

@@ -20,7 +20,6 @@ module Git.Queue (
 import qualified Data.Map as M
 import System.IO
 import System.Process
-import Data.String.Utils
 
 import Utility.SafeCommand
 import Common
@@ -151,7 +150,7 @@ runAction repo (UpdateIndexAction streamers) =
 runAction repo action@(CommandAction {}) =
 	withHandle StdinHandle createProcessSuccess p $ \h -> do
 		fileEncoding h
-		hPutStr h $ join "\0" $ getFiles action
+		hPutStr h $ intercalate "\0" $ getFiles action
 		hClose h
   where
 	p = (proc "xargs" params) { env = gitEnv repo }

Messages.hs

@@ -179,7 +179,7 @@ fileNotFound file = do
 			[ "git-annex:", file, "not found" ]
 
 indent :: String -> String
-indent = join "\n" . map (\l -> "  " ++ l) . lines
+indent = intercalate "\n" . map (\l -> "  " ++ l) . lines
 
 {- Shows a JSON fragment only when in json mode. -}
 maybeShowJSON :: JSON a => [(String, a)] -> Annex ()

Remote.hs

@@ -238,7 +238,7 @@ showTriedRemotes :: [Remote] -> Annex ()
 showTriedRemotes [] = noop
 showTriedRemotes remotes =
 	showLongNote $ "Unable to access these remotes: " ++
-		join ", " (map name remotes)
+		intercalate ", " (map name remotes)
 
 forceTrust :: TrustLevel -> String -> Annex ()
 forceTrust level remotename = do

Remote/Bup.hs

@@ -257,7 +257,7 @@ bup2GitRemote r
   where
 	bits = split ":" r
 	host = Prelude.head bits
-	dir = join ":" $ drop 1 bits
+	dir = intercalate ":" $ drop 1 bits
 	-- "host:~user/dir" is not supported specially by bup;
 	-- "host:dir" is relative to the home directory;
 	-- "host:" goes in ~/.bup

Remote/Helper/Encryptable.hs

@@ -123,7 +123,7 @@ storeCipher c (SharedCipher t) = M.insert "cipher" (toB64 t) c
 storeCipher c (EncryptedCipher t ks) = 
 	M.insert "cipher" (toB64 t) $ M.insert "cipherkeys" (showkeys ks) c
   where
-	showkeys (KeyIds l) = join "," l
+	showkeys (KeyIds l) = intercalate "," l
 
 {- Extracts an StorableCipher from a remote's configuration. -}
 extractCipher :: RemoteConfig -> Maybe StorableCipher

Upgrade/V1.hs

@@ -143,7 +143,7 @@ oldlog2key l
 -- as the v2 key that it is.
 readKey1 :: String -> Key
 readKey1 v
-	| mixup = fromJust $ file2key $ join ":" $ Prelude.tail bits
+	| mixup = fromJust $ file2key $ intercalate ":" $ Prelude.tail bits
 	| otherwise = Key
 		{ keyName = n
 		, keyBackendName = b
@@ -153,7 +153,7 @@ readKey1 v
   where
 	bits = split ":" v
 	b = Prelude.head bits
-	n = join ":" $ drop (if wormy then 3 else 1) bits
+	n = intercalate ":" $ drop (if wormy then 3 else 1) bits
 	t = if wormy
 		then Just (Prelude.read (bits !! 1) :: EpochTime)
 		else Nothing
@@ -165,7 +165,7 @@ readKey1 v
 
 showKey1 :: Key -> String
 showKey1 Key { keyName = n , keyBackendName = b, keySize = s, keyMtime = t } =
-	join ":" $ filter (not . null) [b, showifhere t, showifhere s, n]
+	intercalate ":" $ filter (not . null) [b, showifhere t, showifhere s, n]
   where
 	showifhere Nothing = ""
 	showifhere (Just v) = show v

Utility/Lsof.hs

@@ -32,7 +32,7 @@ setupLsof = do
 	when (isAbsolute cmd) $ do
 		path <- getSearchPath
 		let path' = takeDirectory cmd : path
-		setEnv "PATH" (join [searchPathSeparator] path') True
+		setEnv "PATH" (intercalate [searchPathSeparator] path') True
 
 {- Checks each of the files in a directory to find open files.
  - Note that this will find hard links to files elsewhere that are open. -}

Utility/Rsync.hs

@@ -22,7 +22,7 @@ rsyncShell command = [Param "-e", Param $ unwords $ map escape (toCommand comman
 	{- rsync requires some weird, non-shell like quoting in
 	- here. A doubled single quote inside the single quoted
 	- string is a single quote. -}
-	escape s = "'" ++  join "''" (split "'" s) ++ "'"
+	escape s = "'" ++  intercalate "''" (split "'" s) ++ "'"
 
 {- Runs rsync in server mode to send a file. -}
 rsyncServerSend :: [CommandParam] -> FilePath -> IO Bool