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.

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)