diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,20 @@
+propellor (3.4.0) unstable; urgency=medium
+
+  * Added ConfigurableValue type class, for values that can be used in a
+    config file, or to otherwise configure a program.
+  * The val function converts such values to String.
+  * Removed fromPort and fromIPAddr (use val instead). (API change)
+  * Removed several Show instances that were only used for generating
+    configuration, replacing with ConfigurableValue instances. (API change)
+  * The github mirror of propellor's git repository has been removed,
+    since github's terms of service has started imposing unwanted licensing
+    requirements.
+  * propellor --init: The option to clone propellor's git repository
+    used to use the github mirror, and has been changed to use a different
+    mirror.
+
+ -- Joey Hess <id@joeyh.name>  Wed, 01 Mar 2017 16:44:20 -0400
+
 propellor (3.3.1) unstable; urgency=medium
 
   * Apt: Removed the mirrors.kernel.org line from stdSourcesList etc.
diff --git a/debian/changelog b/debian/changelog
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,20 @@
+propellor (3.4.0) unstable; urgency=medium
+
+  * Added ConfigurableValue type class, for values that can be used in a
+    config file, or to otherwise configure a program.
+  * The val function converts such values to String.
+  * Removed fromPort and fromIPAddr (use val instead). (API change)
+  * Removed several Show instances that were only used for generating
+    configuration, replacing with ConfigurableValue instances. (API change)
+  * The github mirror of propellor's git repository has been removed,
+    since github's terms of service has started imposing unwanted licensing
+    requirements.
+  * propellor --init: The option to clone propellor's git repository
+    used to use the github mirror, and has been changed to use a different
+    mirror.
+
+ -- Joey Hess <id@joeyh.name>  Wed, 01 Mar 2017 16:44:20 -0400
+
 propellor (3.3.1) unstable; urgency=medium
 
   * Apt: Removed the mirrors.kernel.org line from stdSourcesList etc.
diff --git a/propellor.cabal b/propellor.cabal
--- a/propellor.cabal
+++ b/propellor.cabal
@@ -1,5 +1,5 @@
 Name: propellor
-Version: 3.3.1
+Version: 3.4.0
 Cabal-Version: >= 1.8
 License: BSD2
 Maintainer: Joey Hess <id@joeyh.name>
@@ -171,6 +171,7 @@
     Propellor.EnsureProperty
     Propellor.Exception
     Propellor.Types
+    Propellor.Types.ConfigurableValue
     Propellor.Types.Core
     Propellor.Types.Chroot
     Propellor.Types.CmdLine
diff --git a/src/Propellor/DotDir.hs b/src/Propellor/DotDir.hs
--- a/src/Propellor/DotDir.hs
+++ b/src/Propellor/DotDir.hs
@@ -47,10 +47,10 @@
 upstreambranch :: String
 upstreambranch = "upstream/master"
 
--- Using the github mirror of the main propellor repo because
+-- Using the joeyh.name mirror of the main propellor repo because
 -- it is accessible over https for better security.
 netrepo :: String
-netrepo = "https://github.com/joeyh/propellor.git"
+netrepo = "https://git.joeyh.name/propellor.git"
 
 dotPropellor :: IO FilePath
 dotPropellor = do
diff --git a/src/Propellor/Property/Apache.hs b/src/Propellor/Property/Apache.hs
--- a/src/Propellor/Property/Apache.hs
+++ b/src/Propellor/Property/Apache.hs
@@ -72,7 +72,7 @@
 listenPorts ps = "/etc/apache2/ports.conf" `File.hasContent` map portline ps
 	`onChange` restarted
   where
-	portline port = "Listen " ++ fromPort port
+	portline port = "Listen " ++ val port
 
 -- This is a list of config files because different versions of apache
 -- use different filenames. Propellor simply writes them all.
@@ -135,8 +135,8 @@
 -- | Like `virtualHost` but with additional config lines added.
 virtualHost' :: Domain -> Port -> WebRoot -> [ConfigLine] -> RevertableProperty DebianLike DebianLike
 virtualHost' domain port docroot addedcfg = siteEnabled domain $
-	[ "<VirtualHost *:" ++ fromPort port ++ ">"
-	, "ServerName " ++ domain ++ ":" ++ fromPort port
+	[ "<VirtualHost *:" ++ val port ++ ">"
+	, "ServerName " ++ domain ++ ":" ++ val port
 	, "DocumentRoot " ++ docroot
 	, "ErrorLog /var/log/apache2/error.log"
 	, "LogLevel warn"
@@ -202,8 +202,8 @@
 			]
 	sslconffile s = "/etc/apache2/sites-available/ssl/" ++ domain ++ "/" ++ s ++ ".conf"
 	vhost p ls =
-		[ "<VirtualHost *:" ++ fromPort p ++">"
-		, "ServerName " ++ domain ++ ":" ++ fromPort p
+		[ "<VirtualHost *:" ++ val p ++">"
+		, "ServerName " ++ domain ++ ":" ++ val p
 		, "DocumentRoot " ++ docroot
 		, "ErrorLog /var/log/apache2/error.log"
 		, "LogLevel warn"
diff --git a/src/Propellor/Property/Apt.hs b/src/Propellor/Property/Apt.hs
--- a/src/Propellor/Property/Apt.hs
+++ b/src/Propellor/Property/Apt.hs
@@ -452,7 +452,7 @@
 	[ "Explanation: This file added by propellor"
 	, "Package: " ++ p
 	, "Pin: release " ++ suitePin suite
-	, "Pin-Priority: " ++ show pin
+	, "Pin-Priority: " ++ val pin
 	]
 
 dpkgStatus :: FilePath
diff --git a/src/Propellor/Property/Apt/PPA.hs b/src/Propellor/Property/Apt/PPA.hs
--- a/src/Propellor/Property/Apt/PPA.hs
+++ b/src/Propellor/Property/Apt/PPA.hs
@@ -25,8 +25,8 @@
 	, ppaArchive :: String -- ^ The name of the archive.
 	} deriving (Eq, Ord)
 
-instance Show PPA where
-	show p = concat ["ppa:", ppaAccount p, "/", ppaArchive p]
+instance ConfigurableValue PPA where
+	val p = concat ["ppa:", ppaAccount p, "/", ppaArchive p]
 
 instance IsString PPA where
 	-- | Parse strings like "ppa:zfs-native/stable" into a PPA.
@@ -40,9 +40,9 @@
 -- | Adds a PPA to the local system repositories.
 addPpa :: PPA -> Property DebianLike
 addPpa p =
-	cmdPropertyEnv "apt-add-repository" ["--yes", show p] Apt.noninteractiveEnv
+	cmdPropertyEnv "apt-add-repository" ["--yes", val p] Apt.noninteractiveEnv
 	`assume` MadeChange
-	`describe` ("Added PPA " ++ (show p))
+	`describe` ("Added PPA " ++ (val p))
 	`requires` installed
 
 -- | A repository key ID to be downloaded with apt-key.
@@ -52,14 +52,11 @@
 	, akiServer :: String
 	} deriving (Eq, Ord)
 
-instance Show AptKeyId where
-	show k = unwords ["Apt Key", akiName k, akiId k, "from", akiServer k]
-
 -- | Adds an 'AptKeyId' from the specified GPG server.
 addKeyId :: AptKeyId -> Property DebianLike
 addKeyId keyId =
 	check keyTrusted akcmd
-	`describe` (unwords ["Add third-party Apt key", show keyId])
+	`describe` (unwords ["Add third-party Apt key", desc keyId])
   where
 	akcmd =
 		tightenTargets $ cmdProperty "apt-key" ["adv", "--keyserver", akiServer keyId, "--recv-keys", akiId keyId]
@@ -72,10 +69,12 @@
 			nkid = take 8 (akiId keyId)
 		in
 			(isInfixOf [nkid] . pks) <$> readProcess "apt-key" ["list"]
+	desc k = unwords ["Apt Key", akiName k, akiId k, "from", akiServer k]
 
 -- | An Apt source line that apt-add-repository will just add to
--- sources.list. It's also an instance of both 'Show' and 'IsString' to make
--- using 'OverloadedStrings' in the configuration file easier.
+-- sources.list. It's also an instance of both 'ConfigurableValue'
+-- and 'IsString' to make using 'OverloadedStrings' in the configuration
+-- file easier.
 --
 -- | FIXME there's apparently an optional "options" fragment that I've
 -- definitely not parsed here.
@@ -85,8 +84,8 @@
 	, asComponents :: [String] -- ^ The list of components to install from this repository.
 	} deriving (Eq, Ord)
 
-instance Show AptSource where
-	show asrc = unwords ["deb", asURL asrc, asSuite asrc, unwords . asComponents $ asrc]
+instance ConfigurableValue AptSource where
+	val asrc = unwords ["deb", asURL asrc, asSuite asrc, unwords . asComponents $ asrc]
 
 instance IsString AptSource where
 	fromString s =
@@ -103,7 +102,7 @@
 addRepository (AptRepositoryPPA p) = addPpa p
 addRepository (AptRepositorySource src) =
 	check repoExists addSrc
-	`describe` unwords ["Adding APT repository", show src]
+	`describe` unwords ["Adding APT repository", val src]
 	`requires` installed
   where
 	allSourceLines =
@@ -112,4 +111,4 @@
 		. filter (not . isPrefixOf "#")
 		. filter (/= "") . lines <$> allSourceLines
 	repoExists = isInfixOf [src] <$> activeSources
-	addSrc = cmdProperty "apt-add-source" [show src]
+	addSrc = cmdProperty "apt-add-source" [val src]
diff --git a/src/Propellor/Property/Attic.hs b/src/Propellor/Property/Attic.hs
--- a/src/Propellor/Property/Attic.hs
+++ b/src/Propellor/Property/Attic.hs
@@ -131,11 +131,11 @@
 -- passed to the `backup` property, they will run attic prune to clean out
 -- generations not specified here.
 keepParam :: KeepPolicy -> AtticParam
-keepParam (KeepHours n) = "--keep-hourly=" ++ show n
-keepParam (KeepDays n) = "--keep-daily=" ++ show n
-keepParam (KeepWeeks n) = "--keep-daily=" ++ show n
-keepParam (KeepMonths n) = "--keep-monthly=" ++ show n
-keepParam (KeepYears n) = "--keep-yearly=" ++ show n
+keepParam (KeepHours n) = "--keep-hourly=" ++ val n
+keepParam (KeepDays n) = "--keep-daily=" ++ val n
+keepParam (KeepWeeks n) = "--keep-daily=" ++ val n
+keepParam (KeepMonths n) = "--keep-monthly=" ++ val n
+keepParam (KeepYears n) = "--keep-yearly=" ++ val n
 
 -- | Policy for backup generations to keep. For example, KeepDays 30 will
 -- keep the latest backup for each day when a backup was made, and keep the
diff --git a/src/Propellor/Property/Borg.hs b/src/Propellor/Property/Borg.hs
--- a/src/Propellor/Property/Borg.hs
+++ b/src/Propellor/Property/Borg.hs
@@ -137,11 +137,11 @@
 -- passed to the `backup` property, they will run borg prune to clean out
 -- generations not specified here.
 keepParam :: KeepPolicy -> BorgParam
-keepParam (KeepHours n) = "--keep-hourly=" ++ show n
-keepParam (KeepDays n) = "--keep-daily=" ++ show n
-keepParam (KeepWeeks n) = "--keep-daily=" ++ show n
-keepParam (KeepMonths n) = "--keep-monthly=" ++ show n
-keepParam (KeepYears n) = "--keep-yearly=" ++ show n
+keepParam (KeepHours n) = "--keep-hourly=" ++ val n
+keepParam (KeepDays n) = "--keep-daily=" ++ val n
+keepParam (KeepWeeks n) = "--keep-daily=" ++ val n
+keepParam (KeepMonths n) = "--keep-monthly=" ++ val n
+keepParam (KeepYears n) = "--keep-yearly=" ++ val n
 
 -- | Policy for backup generations to keep. For example, KeepDays 30 will
 -- keep the latest backup for each day when a backup was made, and keep the
diff --git a/src/Propellor/Property/Ccache.hs b/src/Propellor/Property/Ccache.hs
--- a/src/Propellor/Property/Ccache.hs
+++ b/src/Propellor/Property/Ccache.hs
@@ -76,7 +76,7 @@
 limitToParams (MaxSize s) = case maxSizeParam s of
 	Just param -> [Right param]
 	Nothing -> [Left $ "unable to parse data size " ++ s]
-limitToParams (MaxFiles f) = [Right $ "--max-files=" ++ show f]
+limitToParams (MaxFiles f) = [Right $ "--max-files=" ++ val f]
 limitToParams (l1 :+ l2) = limitToParams l1 <> limitToParams l2
 
 -- | Configures a ccache in /var/cache for a group
diff --git a/src/Propellor/Property/Dns.hs b/src/Propellor/Property/Dns.hs
--- a/src/Propellor/Property/Dns.hs
+++ b/src/Propellor/Property/Dns.hs
@@ -250,7 +250,7 @@
 	cfgline f v = "\t" ++ f ++ " " ++ v ++ ";"
 	ipblock name l =
 		[ "\t" ++ name ++ " {" ] ++
-		(map (\ip -> "\t\t" ++ fromIPAddr ip ++ ";") l) ++
+		(map (\ip -> "\t\t" ++ val ip ++ ";") l) ++
 		[ "\t};" ]
 	mastersblock
 		| null (confMasters c) = []
@@ -307,17 +307,17 @@
 rValue (Address (IPv4 addr)) = Just addr
 rValue (Address (IPv6 addr)) = Just addr
 rValue (CNAME d) = Just $ dValue d
-rValue (MX pri d) = Just $ show pri ++ " " ++ dValue d
+rValue (MX pri d) = Just $ val pri ++ " " ++ dValue d
 rValue (NS d) = Just $ dValue d
 rValue (SRV priority weight port target) = Just $ unwords
-	[ show priority
-	, show weight
-	, show port
+	[ val priority
+	, val weight
+	, val port
 	, dValue target
 	]
 rValue (SSHFP x y s) = Just $ unwords
-	[ show x
-	, show y
+	[ val x
+	, val y
 	, s
 	]
 rValue (INCLUDE f) = Just f
diff --git a/src/Propellor/Property/Docker.hs b/src/Propellor/Property/Docker.hs
--- a/src/Propellor/Property/Docker.hs
+++ b/src/Propellor/Property/Docker.hs
@@ -323,7 +323,7 @@
 	toPublish :: p -> String
 
 instance Publishable (Bound Port) where
-	toPublish p = fromPort (hostSide p) ++ ":" ++ fromPort (containerSide p)
+	toPublish p = val (hostSide p) ++ ":" ++ val (containerSide p)
 
 -- | string format: ip:hostPort:containerPort | ip::containerPort | hostPort:containerPort
 instance Publishable String where
@@ -660,10 +660,10 @@
 listImages = map ImageUID . lines <$> readProcess dockercmd ["images", "--all", "--quiet"]
 
 runProp :: String -> RunParam -> Property (HasInfo + Linux)
-runProp field val = tightenTargets $ pureInfoProperty (param) $
+runProp field v = tightenTargets $ pureInfoProperty (param) $
 	mempty { _dockerRunParams = [DockerRunParam (\_ -> "--"++param)] }
   where
-	param = field++"="++val
+	param = field++"="++v
 
 genProp :: String -> (HostName -> RunParam) -> Property (HasInfo + Linux)
 genProp field mkval = tightenTargets $ pureInfoProperty field $
diff --git a/src/Propellor/Property/File.hs b/src/Propellor/Property/File.hs
--- a/src/Propellor/Property/File.hs
+++ b/src/Propellor/Property/File.hs
@@ -20,6 +20,12 @@
 	(\_oldcontent -> newcontent) f
 
 -- | Ensures that a line is present in a file, adding it to the end if not.
+--
+-- For example:
+--
+-- >	& "/etc/default/daemon.conf" `File.containsLine` ("cachesize = " ++ val 1024)
+--
+-- The above example uses `val` to serialize a `ConfigurableValue`
 containsLine :: FilePath -> Line -> Property UnixLike
 f `containsLine` l = f `containsLines` [l]
 
diff --git a/src/Propellor/Property/Firewall.hs b/src/Propellor/Property/Firewall.hs
--- a/src/Propellor/Property/Firewall.hs
+++ b/src/Propellor/Property/Firewall.hs
@@ -15,7 +15,6 @@
 	TCPFlag(..),
 	Frequency(..),
 	IPWithMask(..),
-	fromIPWithMask
 ) where
 
 import Data.Monoid
@@ -44,16 +43,16 @@
 
 toIpTable :: Rule -> [CommandParam]
 toIpTable r =  map Param $
-	fromChain (ruleChain r) :
+	val (ruleChain r) :
 	toIpTableArg (ruleRules r) ++
-	["-t", fromTable (ruleTable r), "-j", fromTarget (ruleTarget r)]
+	["-t", val (ruleTable r), "-j", val (ruleTarget r)]
 
 toIpTableArg :: Rules -> [String]
 toIpTableArg Everything = []
 toIpTableArg (Proto proto) = ["-p", map toLower $ show proto]
-toIpTableArg (DPort port) = ["--dport", fromPort port]
+toIpTableArg (DPort port) = ["--dport", val port]
 toIpTableArg (DPortRange (portf, portt)) =
-	["--dport", fromPort portf ++ ":" ++ fromPort portt]
+	["--dport", val portf ++ ":" ++ val portt]
 toIpTableArg (InIFace iface) = ["-i", iface]
 toIpTableArg (OutIFace iface) = ["-o", iface]
 toIpTableArg (Ctstate states) =
@@ -64,12 +63,12 @@
 toIpTableArg (ICMPType i) =
 	[ "-m"
 	, "icmp"
-	, "--icmp-type", fromICMPTypeMatch i
+	, "--icmp-type", val i
 	]
 toIpTableArg (RateLimit f) =
 	[ "-m"
 	, "limit"
-	, "--limit", fromFrequency f
+	, "--limit", val f
 	]
 toIpTableArg (TCPFlags m c) =
 	[ "-m"
@@ -87,30 +86,30 @@
 	]
 toIpTableArg (Source ipwm) =
 	[ "-s"
-	, intercalate "," (map fromIPWithMask ipwm)
+	, intercalate "," (map val ipwm)
 	]
 toIpTableArg (Destination ipwm) =
 	[ "-d"
-	, intercalate "," (map fromIPWithMask ipwm)
+	, intercalate "," (map val ipwm)
 	]
 toIpTableArg (NotDestination ipwm) =
 	[ "!"
 	, "-d"
-	, intercalate "," (map fromIPWithMask ipwm)
+	, intercalate "," (map val ipwm)
 	]
 toIpTableArg (NatDestination ip mport) =
 	[ "--to-destination"
-	, fromIPAddr ip ++ maybe "" (\p -> ":" ++ fromPort p) mport
+	, val ip ++ maybe "" (\p -> ":" ++ val p) mport
 	]
 toIpTableArg (r :- r') = toIpTableArg r <> toIpTableArg r'
 
 data IPWithMask = IPWithNoMask IPAddr | IPWithIPMask IPAddr IPAddr | IPWithNumMask IPAddr Int
 	deriving (Eq, Show)
 
-fromIPWithMask :: IPWithMask -> String
-fromIPWithMask (IPWithNoMask ip) = fromIPAddr ip
-fromIPWithMask (IPWithIPMask ip ipm) = fromIPAddr ip ++ "/" ++ fromIPAddr ipm
-fromIPWithMask (IPWithNumMask ip m) = fromIPAddr ip ++ "/" ++ show m
+instance ConfigurableValue IPWithMask where
+	val (IPWithNoMask ip) = val ip
+	val (IPWithIPMask ip ipm) = val ip ++ "/" ++ val ipm
+	val (IPWithNumMask ip m) = val ip ++ "/" ++ val m
 
 data Rule = Rule
 	{ ruleChain  :: Chain
@@ -122,33 +121,33 @@
 data Table = Filter | Nat | Mangle | Raw | Security
 	deriving (Eq, Show)
 
-fromTable :: Table -> String
-fromTable Filter = "filter"
-fromTable Nat = "nat"
-fromTable Mangle = "mangle"
-fromTable Raw = "raw"
-fromTable Security = "security"
+instance ConfigurableValue Table where
+	val Filter = "filter"
+	val Nat = "nat"
+	val Mangle = "mangle"
+	val Raw = "raw"
+	val Security = "security"
 
 data Target = ACCEPT | REJECT | DROP | LOG | TargetCustom String
 	deriving (Eq, Show)
 
-fromTarget :: Target -> String
-fromTarget ACCEPT = "ACCEPT"
-fromTarget REJECT = "REJECT"
-fromTarget DROP = "DROP"
-fromTarget LOG = "LOG"
-fromTarget (TargetCustom t) = t
+instance ConfigurableValue Target where
+	val ACCEPT = "ACCEPT"
+	val REJECT = "REJECT"
+	val DROP = "DROP"
+	val LOG = "LOG"
+	val (TargetCustom t) = t
 
 data Chain = INPUT | OUTPUT | FORWARD | PREROUTING | POSTROUTING | ChainCustom String
 	deriving (Eq, Show)
 
-fromChain :: Chain -> String
-fromChain INPUT = "INPUT"
-fromChain OUTPUT = "OUTPUT"
-fromChain FORWARD = "FORWARD"
-fromChain PREROUTING = "PREROUTING"
-fromChain POSTROUTING = "POSTROUTING"
-fromChain (ChainCustom c) = c
+instance ConfigurableValue Chain where
+	val INPUT = "INPUT"
+	val OUTPUT = "OUTPUT"
+	val FORWARD = "FORWARD"
+	val PREROUTING = "PREROUTING"
+	val POSTROUTING = "POSTROUTING"
+	val (ChainCustom c) = c
 
 data Proto = TCP | UDP | ICMP
 	deriving (Eq, Show)
@@ -159,15 +158,15 @@
 data ICMPTypeMatch = ICMPTypeName String | ICMPTypeCode Int
 	deriving (Eq, Show)
 
-fromICMPTypeMatch :: ICMPTypeMatch -> String
-fromICMPTypeMatch (ICMPTypeName t) = t
-fromICMPTypeMatch (ICMPTypeCode c) = show c
+instance ConfigurableValue ICMPTypeMatch where
+	val (ICMPTypeName t) = t
+	val (ICMPTypeCode c) = val c
 
 data Frequency = NumBySecond Int
 	deriving (Eq, Show)
 
-fromFrequency :: Frequency -> String
-fromFrequency (NumBySecond n) = show n ++ "/second"
+instance ConfigurableValue Frequency where
+	val (NumBySecond n) = val n ++ "/second"
 
 type TCPFlagMask = [TCPFlag]
 
diff --git a/src/Propellor/Property/FreeBSD/Poudriere.hs b/src/Propellor/Property/FreeBSD/Poudriere.hs
--- a/src/Propellor/Property/FreeBSD/Poudriere.hs
+++ b/src/Propellor/Property/FreeBSD/Poudriere.hs
@@ -19,6 +19,7 @@
 
 newtype PoudriereConfigured = PoudriereConfigured String
 	deriving (Typeable, Monoid, Show)
+
 instance IsInfo PoudriereConfigured where
 	propagateInfo _ = False
 
@@ -68,7 +69,7 @@
 			nx <- liftIO $ not <$> jailExists j
 			return $ c && nx
 
-		(cmd, args) = poudriereCommand "jail"  ["-c", "-j", name, "-a", show arch, "-v", show version]
+		(cmd, args) = poudriereCommand "jail"  ["-c", "-j", name, "-a", val arch, "-v", val version]
 		createJail = cmdProperty cmd args
 	in
 		check chk createJail
@@ -101,10 +102,11 @@
 data Jail = Jail String FBSDVersion PoudriereArch
 
 data PoudriereArch = I386 | AMD64 deriving (Eq)
-instance Show PoudriereArch where
-	show I386 = "i386"
-	show AMD64 = "amd64"
 
+instance ConfigurableValue PoudriereArch where
+	val I386 = "i386"
+	val AMD64 = "amd64"
+
 fromArchitecture :: Architecture -> PoudriereArch
 fromArchitecture X86_64 = AMD64
 fromArchitecture X86_32 = I386
@@ -127,7 +129,7 @@
 	toAssoc (PoudriereZFS (ZFS.ZFS (ZFS.ZPool pool) dataset) _) =
 		[ ("NO_ZFS", "no")
 		, ("ZPOOL", pool)
-		, ("ZROOTFS", show dataset)
+		, ("ZROOTFS", val dataset)
 		]
 
 type ConfigLine = String
diff --git a/src/Propellor/Property/Grub.hs b/src/Propellor/Property/Grub.hs
--- a/src/Propellor/Property/Grub.hs
+++ b/src/Propellor/Property/Grub.hs
@@ -69,7 +69,7 @@
 	& File.dirExists "/boot/grub"
 	& "/boot/grub/menu.lst" `File.hasContent`
 		[ "default 1" 
-		, "timeout " ++ show timeout
+		, "timeout " ++ val timeout
 		, ""
 		, "title grub-xen shim"
 		, "root (" ++ rootdev ++ ")"
diff --git a/src/Propellor/Property/Logcheck.hs b/src/Propellor/Property/Logcheck.hs
--- a/src/Propellor/Property/Logcheck.hs
+++ b/src/Propellor/Property/Logcheck.hs
@@ -16,21 +16,21 @@
 data ReportLevel = Workstation | Server | Paranoid
 type Service = String
 
-instance Show ReportLevel where
-	show Workstation = "workstation"
-	show Server = "server"
-	show Paranoid = "paranoid"
+instance ConfigurableValue ReportLevel where
+	val Workstation = "workstation"
+	val Server = "server"
+	val Paranoid = "paranoid"
 
 -- The common prefix used by default in syslog lines.
 defaultPrefix :: String
 defaultPrefix = "^\\w{3} [ :[:digit:]]{11} [._[:alnum:]-]+ "
 
 ignoreFilePath :: ReportLevel -> Service -> FilePath
-ignoreFilePath t n = "/etc/logcheck/ignore.d." ++ (show t) </> n
+ignoreFilePath t n = "/etc/logcheck/ignore.d." ++ (val t) </> n
 
 ignoreLines :: ReportLevel -> Service -> [String] -> Property UnixLike
 ignoreLines t n ls = (ignoreFilePath t n) `File.containsLines` ls
-	`describe` ("logcheck ignore lines for " ++ n ++ "(" ++ (show t) ++ ")")
+	`describe` ("logcheck ignore lines for " ++ n ++ "(" ++ val t ++ ")")
 
 installed :: Property DebianLike
 installed = Apt.installed ["logcheck"]
diff --git a/src/Propellor/Property/Obnam.hs b/src/Propellor/Property/Obnam.hs
--- a/src/Propellor/Property/Obnam.hs
+++ b/src/Propellor/Property/Obnam.hs
@@ -150,7 +150,7 @@
 	go (KeepWeeks n) = mk n 'w'
 	go (KeepMonths n) = mk n 'm'
 	go (KeepYears n) = mk n 'y'
-	mk n c = show n ++ [c]
+	mk n c = val n ++ [c]
 
 isKeepParam :: ObnamParam -> Bool
 isKeepParam p = "--keep=" `isPrefixOf` p
diff --git a/src/Propellor/Property/OpenId.hs b/src/Propellor/Property/OpenId.hs
--- a/src/Propellor/Property/OpenId.hs
+++ b/src/Propellor/Property/OpenId.hs
@@ -28,7 +28,7 @@
   where
 	baseurl = hn ++ case mp of
 		Nothing -> ""
-		Just p -> ':' : fromPort p
+		Just p -> ':' : val p
 	url = "http://"++baseurl++"/simpleid"
 	desc = "openid provider " ++ url
 	setbaseurl l
diff --git a/src/Propellor/Property/Parted.hs b/src/Propellor/Property/Parted.hs
--- a/src/Propellor/Property/Parted.hs
+++ b/src/Propellor/Property/Parted.hs
@@ -30,14 +30,14 @@
 import System.Posix.Files
 
 class PartedVal a where
-	val :: a -> String
+	pval :: a -> String
 
 -- | Types of partition tables supported by parted.
 data TableType = MSDOS | GPT | AIX | AMIGA | BSD | DVH | LOOP | MAC | PC98 | SUN
 	deriving (Show)
 
 instance PartedVal TableType where
-	val = map toLower . show
+	pval = map toLower . show
 
 -- | A disk's partition table.
 data PartTable = PartTable TableType [Partition]
@@ -82,9 +82,9 @@
 	deriving (Show)
 
 instance PartedVal PartType where
-	val Primary = "primary"
-	val Logical = "logical"
-	val Extended = "extended"
+	pval Primary = "primary"
+	pval Logical = "logical"
+	pval Extended = "extended"
 
 -- | All partition sizing is done in megabytes, so that parted can
 -- automatically lay out the partitions.
@@ -94,11 +94,11 @@
 	deriving (Show)
 
 instance PartedVal PartSize where
-	val (MegaBytes n)
-		| n > 0 = show n ++ "MB"
+	pval (MegaBytes n)
+		| n > 0 = val n ++ "MB"
 		-- parted can't make partitions smaller than 1MB;
 		-- avoid failure in edge cases
-		| otherwise = show "1MB"
+		| otherwise = "1MB"
 
 -- | Rounds up to the nearest MegaByte.
 toPartSize :: ByteSize -> PartSize
@@ -119,33 +119,33 @@
 	deriving (Show)
 
 instance PartedVal PartFlag where
-	val BootFlag = "boot"
-	val RootFlag = "root"
-	val SwapFlag = "swap"
-	val HiddenFlag = "hidden"
-	val RaidFlag = "raid"
-	val LvmFlag = "lvm"
-	val LbaFlag = "lba"
-	val LegacyBootFlag = "legacy_boot"
-	val IrstFlag = "irst"
-	val EspFlag = "esp"
-	val PaloFlag = "palo"
+	pval BootFlag = "boot"
+	pval RootFlag = "root"
+	pval SwapFlag = "swap"
+	pval HiddenFlag = "hidden"
+	pval RaidFlag = "raid"
+	pval LvmFlag = "lvm"
+	pval LbaFlag = "lba"
+	pval LegacyBootFlag = "legacy_boot"
+	pval IrstFlag = "irst"
+	pval EspFlag = "esp"
+	pval PaloFlag = "palo"
 
 instance PartedVal Bool where
-	val True = "on"
-	val False = "off"
+	pval True = "on"
+	pval False = "off"
 
 instance PartedVal Partition.Fs where
-	val Partition.EXT2 = "ext2"
-	val Partition.EXT3 = "ext3"
-	val Partition.EXT4 = "ext4"
-	val Partition.BTRFS = "btrfs"
-	val Partition.REISERFS = "reiserfs"
-	val Partition.XFS = "xfs"
-	val Partition.FAT = "fat"
-	val Partition.VFAT = "vfat"
-	val Partition.NTFS = "ntfs"
-	val Partition.LinuxSwap = "linux-swap"
+	pval Partition.EXT2 = "ext2"
+	pval Partition.EXT3 = "ext3"
+	pval Partition.EXT4 = "ext4"
+	pval Partition.BTRFS = "btrfs"
+	pval Partition.REISERFS = "reiserfs"
+	pval Partition.XFS = "xfs"
+	pval Partition.FAT = "fat"
+	pval Partition.VFAT = "vfat"
+	pval Partition.NTFS = "ntfs"
+	pval Partition.LinuxSwap = "linux-swap"
 
 data Eep = YesReallyDeleteDiskContents
 
@@ -168,19 +168,19 @@
 	partedparams = concat $ mklabel : mkparts (1 :: Integer) mempty parts []
 	format (p, dev) = Partition.formatted' (partMkFsOpts p)
 		Partition.YesReallyFormatPartition (partFs p) dev
-	mklabel = ["mklabel", val tabletype]
+	mklabel = ["mklabel", pval tabletype]
 	mkflag partnum (f, b) =
 		[ "set"
 		, show partnum
-		, val f
-		, val b
+		, pval f
+		, pval b
 		]
 	mkpart partnum offset p =
 		[ "mkpart"
-		, val (partType p)
-		, val (partFs p)
-		, val offset
-		, val (offset <> partSize p)
+		, pval (partType p)
+		, pval (partFs p)
+		, pval offset
+		, pval (offset <> partSize p)
 		] ++ case partName p of
 			Just n -> ["name", show partnum, n]
 			Nothing -> []
diff --git a/src/Propellor/Property/Sbuild.hs b/src/Propellor/Property/Sbuild.hs
--- a/src/Propellor/Property/Sbuild.hs
+++ b/src/Propellor/Property/Sbuild.hs
@@ -111,8 +111,8 @@
 -- the same suite and the same architecture, so neither do we
 data SbuildSchroot = SbuildSchroot Suite Architecture
 
-instance Show SbuildSchroot where
-	show (SbuildSchroot suite arch) = suite ++ "-" ++ architectureToDebianArchString arch
+instance ConfigurableValue SbuildSchroot where
+	val (SbuildSchroot suite arch) = suite ++ "-" ++ architectureToDebianArchString arch
 
 -- | Whether an sbuild schroot should use ccache during builds
 --
@@ -151,7 +151,7 @@
   where
 	go :: Property DebianLike
 	go = check (unpopulated (schrootRoot s) <||> ispartial) $
-		property' ("built sbuild schroot for " ++ show s) make
+		property' ("built sbuild schroot for " ++ val s) make
 	make w = do
 		de <- liftIO standardPathEnv
 		let params = Param <$>
@@ -170,18 +170,18 @@
 	-- TODO we should kill any sessions still using the chroot
 	-- before destroying it (as suggested by sbuild-destroychroot)
 	deleted = check (not <$> unpopulated (schrootRoot s)) $
-		property ("no sbuild schroot for " ++ show s) $ do
+		property ("no sbuild schroot for " ++ val s) $ do
 			liftIO $ removeChroot $ schrootRoot s
 			liftIO $ nukeFile
-				("/etc/sbuild/chroot" </> show s ++ "-sbuild")
+				("/etc/sbuild/chroot" </> val s ++ "-sbuild")
 			makeChange $ nukeFile (schrootConf s)
 
 	enhancedConf =
-		combineProperties ("enhanced schroot conf for " ++ show s) $ props
+		combineProperties ("enhanced schroot conf for " ++ val s) $ props
 			& aliasesLine
 			-- enable ccache and eatmydata for speed
 			& ConfFile.containsIniSetting (schrootConf s)
-				( show s ++ "-sbuild"
+				( val s ++ "-sbuild"
 				, "command-prefix"
 				, intercalate "," commandPrefix
 				)
@@ -196,7 +196,7 @@
 			then ensureProperty w $
 				ConfFile.containsIniSetting
 					(schrootConf s)
-					( show s ++ "-sbuild"
+					( val s ++ "-sbuild"
 					, "aliases"
 					, aliases
 					)
@@ -263,7 +263,7 @@
 updated :: SbuildSchroot -> Property DebianLike
 updated s@(SbuildSchroot suite arch) =
 	check (doesDirectoryExist (schrootRoot s)) $ go
-	`describe` ("updated schroot for " ++ show s)
+	`describe` ("updated schroot for " ++ val s)
 	`requires` installed
   where
 	go :: Property DebianLike
@@ -283,13 +283,13 @@
 -- given suite and architecture, so we don't need the suffix to be random.
 fixConfFile :: SbuildSchroot -> Property UnixLike
 fixConfFile s@(SbuildSchroot suite arch) =
-	property' ("schroot for " ++ show s ++ " config file fixed") $ \w -> do
+	property' ("schroot for " ++ val s ++ " config file fixed") $ \w -> do
 		confs <- liftIO $ dirContents dir
 		let old = concat $ filter (tempPrefix `isPrefixOf`) confs
 		liftIO $ moveFile old new
 		liftIO $ moveFile
-			("/etc/sbuild/chroot" </> show s ++ "-propellor")
-			("/etc/sbuild/chroot" </> show s ++ "-sbuild")
+			("/etc/sbuild/chroot" </> val s ++ "-propellor")
+			("/etc/sbuild/chroot" </> val s ++ "-sbuild")
 		ensureProperty w $
 			File.fileProperty "replace dummy suffix" (map munge) new
   where
@@ -361,10 +361,10 @@
 
 	orig = "/etc/schroot/sbuild"
 	dir = "/etc/schroot/piuparts"
-	sec = show s ++ "-piuparts"
+	sec = val s ++ "-piuparts"
 	f = schrootPiupartsConf s
 	munge = replace "-sbuild]" "-piuparts]"
-	desc = "piuparts schroot conf for " ++ show s
+	desc = "piuparts schroot conf for " ++ val s
 
 	-- normally the piuparts schroot conf has no aliases, but we have to add
 	-- one, for dgit compatibility, if this is the default sid chroot
diff --git a/src/Propellor/Property/SiteSpecific/JoeySites.hs b/src/Propellor/Property/SiteSpecific/JoeySites.hs
--- a/src/Propellor/Property/SiteSpecific/JoeySites.hs
+++ b/src/Propellor/Property/SiteSpecific/JoeySites.hs
@@ -314,9 +314,9 @@
 
 apachecfg :: HostName -> Apache.ConfigFile -> Apache.ConfigFile
 apachecfg hn middle =
-	[ "<VirtualHost *:"++show port++">"
+	[ "<VirtualHost *:" ++ val port ++ ">"
 	, "  ServerAdmin grue@joeyh.name"
-	, "  ServerName "++hn++":"++show port
+	, "  ServerName "++hn++":" ++ val port
 	]
 	++ middle ++
 	[ ""
@@ -329,7 +329,7 @@
 	, "</VirtualHost>"
 	]
 	  where
-		port = 80 :: Int
+		port = Port 80
 
 gitAnnexDistributor :: Property (HasInfo + DebianLike)
 gitAnnexDistributor = combineProperties "git-annex distributor, including rsync server and signer" $ props
@@ -405,8 +405,6 @@
 	& githubKeys
 	& Cron.niceJob "github-backup run" (Cron.Times "30 4 * * *") (User "joey")
 		"/home/joey/lib/backup" backupcmd
-	& Cron.niceJob "gitriddance" (Cron.Times "30 4 * * *") (User "joey")
-		"/home/joey/lib/backup" gitriddancecmd
   where
 	backupcmd = intercalate "&&" $
 		[ "mkdir -p github"
@@ -414,11 +412,6 @@
 		, ". $HOME/.github-keys"
 		, "github-backup joeyh"
 		]
-	gitriddancecmd = intercalate "&&" $
-		[ "cd github"
-		, ". $HOME/.github-keys"
-		] ++ map gitriddance githubMirrors
-	gitriddance (r, msg) = "(cd " ++ r ++ " && gitriddance " ++ shellEscape msg ++ ")"
 
 githubKeys :: Property (HasInfo + UnixLike)
 githubKeys =
@@ -426,19 +419,6 @@
 	in File.hasPrivContent f anyContext
 		`onChange` File.ownerGroup f (User "joey") (Group "joey")
 
-
--- these repos are only mirrored on github, I don't want
--- all the proprietary features
-githubMirrors :: [(String, String)]
-githubMirrors =
-	[ ("ikiwiki", plzuseurl "http://ikiwiki.info/todo/")
-	, ("git-annex", plzuseurl "http://git-annex.branchable.com/todo/")
-	, ("myrepos", plzuseurl "http://myrepos.branchable.com/todo/")
-	, ("propellor", plzuseurl "http://propellor.branchable.com/todo/")
-	, ("etckeeper", plzuseurl "http://etckeeper.branchable.com/todo/")
-	]
-  where
-	plzuseurl u = "Please submit changes to " ++ u ++ " instead of using github pull requests, which are not part of my workflow. Just open a todo item there and link to a git repository containing your changes. Did you know, git is a distributed system? The git repository doesn't even need to be on github! Please send any complaints to Github; they don't allow turning off pull requests or redirecting them elsewhere.  -- A robot acting on behalf of Joey Hess"
 
 rsyncNetBackup :: [Host] -> Property DebianLike
 rsyncNetBackup hosts = Cron.niceJob "rsync.net copied in daily" (Cron.Times "30 5 * * *")
diff --git a/src/Propellor/Property/Ssh.hs b/src/Propellor/Property/Ssh.hs
--- a/src/Propellor/Property/Ssh.hs
+++ b/src/Propellor/Property/Ssh.hs
@@ -69,11 +69,11 @@
 setSshdConfigBool setting allowed = setSshdConfig setting (sshBool allowed)
 
 setSshdConfig :: ConfigKeyword -> String -> Property DebianLike
-setSshdConfig setting val = File.fileProperty desc f sshdConfig
+setSshdConfig setting v = File.fileProperty desc f sshdConfig
 	`onChange` restarted
   where
-	desc = unwords [ "ssh config:", setting, val ]
-	cfgline = setting ++ " " ++ val
+	desc = unwords [ "ssh config:", setting, v ]
+	cfgline = setting ++ " " ++ v
 	wantedline s
 		| s == cfgline = True
 		| (setting ++ " ") `isPrefixOf` s = False
@@ -120,7 +120,7 @@
 listenPort :: Port -> RevertableProperty DebianLike DebianLike
 listenPort port = enable <!> disable
   where
-	portline = "Port " ++ fromPort port
+	portline = "Port " ++ val port
 	enable = sshdConfig `File.containsLine` portline
 		`describe` ("ssh listening on " ++ portline)
 		`onChange` restarted
diff --git a/src/Propellor/Property/Systemd.hs b/src/Propellor/Property/Systemd.hs
--- a/src/Propellor/Property/Systemd.hs
+++ b/src/Propellor/Property/Systemd.hs
@@ -421,7 +421,7 @@
 	toPublish :: a -> String
 
 instance Publishable Port where
-	toPublish port = fromPort port
+	toPublish port = val port
 
 instance Publishable (Bound Port) where
 	toPublish v = toPublish (hostSide v) ++ ":" ++ toPublish (containerSide v)
diff --git a/src/Propellor/Property/Tor.hs b/src/Propellor/Property/Tor.hs
--- a/src/Propellor/Property/Tor.hs
+++ b/src/Propellor/Property/Tor.hs
@@ -128,7 +128,7 @@
 
 hiddenService' :: HiddenServiceName -> [Port] -> Property DebianLike
 hiddenService' hn ports = ConfFile.adjustSection
-	(unwords ["hidden service", hn, "available on ports", intercalate "," (map fromPort ports')])
+	(unwords ["hidden service", hn, "available on ports", intercalate "," (map val ports')])
 	(== oniondir)
 	(not . isPrefixOf "HiddenServicePort")
 	(const (oniondir : onionports))
@@ -139,7 +139,7 @@
 	oniondir = unwords ["HiddenServiceDir", varLib </> hn]
 	onionports = map onionport ports'
 	ports' = sort ports
-	onionport port = unwords ["HiddenServicePort", fromPort port, "127.0.0.1:" ++ fromPort port]
+	onionport port = unwords ["HiddenServicePort", val port, "127.0.0.1:" ++ val port]
 
 -- | Same as `hiddenService` but also causes propellor to display
 -- the onion address of the hidden service.
diff --git a/src/Propellor/Property/Unbound.hs b/src/Propellor/Property/Unbound.hs
--- a/src/Propellor/Property/Unbound.hs
+++ b/src/Propellor/Property/Unbound.hs
@@ -133,10 +133,10 @@
 	IPv6 _ -> genAddress' "AAAA" dom ttl addr
 
 genAddress' :: String -> BindDomain -> Maybe Int -> IPAddr -> String
-genAddress' recordtype dom ttl addr = dValue dom ++ " " ++ maybe "" (\ttl' -> show ttl' ++ " ") ttl ++ "IN " ++ recordtype ++ " " ++ fromIPAddr addr
+genAddress' recordtype dom ttl addr = dValue dom ++ " " ++ maybe "" (\ttl' -> val ttl' ++ " ") ttl ++ "IN " ++ recordtype ++ " " ++ val addr
 
 genMX :: BindDomain -> Int -> BindDomain -> String
-genMX dom priority dest = dValue dom ++ " " ++ "MX" ++ " " ++ show priority ++ " " ++ dValue dest
+genMX dom priority dest = dValue dom ++ " " ++ "MX" ++ " " ++ val priority ++ " " ++ dValue dest
 
 genPTR :: BindDomain -> ReverseIP -> String
 genPTR dom revip = revip ++ ". " ++ "PTR" ++ " " ++ dValue dom
diff --git a/src/Propellor/Spin.hs b/src/Propellor/Spin.hs
--- a/src/Propellor/Spin.hs
+++ b/src/Propellor/Spin.hs
@@ -169,7 +169,7 @@
 					warningMessage $ "DNS seems out of date for " ++ target ++ " (" ++ why ++ "); using IP address from configuration instead."
 					return ip
 
-	configips = map fromIPAddr $ mapMaybe getIPAddr $
+	configips = map val $ mapMaybe getIPAddr $
 		S.toList $ fromDnsInfo $ fromInfo $ hostInfo hst
 
 -- Update the privdata, repo url, and git repo over the ssh
diff --git a/src/Propellor/Types.hs b/src/Propellor/Types.hs
--- a/src/Propellor/Types.hs
+++ b/src/Propellor/Types.hs
@@ -36,6 +36,7 @@
 	, adjustPropertySatisfy
 	-- * Other included types
 	, module Propellor.Types.OS
+	, module Propellor.Types.ConfigurableValue
 	, module Propellor.Types.Dns
 	, module Propellor.Types.Result
 	, module Propellor.Types.ZFS
@@ -46,6 +47,7 @@
 import Propellor.Types.Core
 import Propellor.Types.Info
 import Propellor.Types.OS
+import Propellor.Types.ConfigurableValue
 import Propellor.Types.Dns
 import Propellor.Types.Result
 import Propellor.Types.MetaTypes
diff --git a/src/Propellor/Types/ConfigurableValue.hs b/src/Propellor/Types/ConfigurableValue.hs
new file mode 100644
--- /dev/null
+++ b/src/Propellor/Types/ConfigurableValue.hs
@@ -0,0 +1,44 @@
+{-# LANGUAGE TypeSynonymInstances, FlexibleInstances #-}
+
+module Propellor.Types.ConfigurableValue where
+
+import Data.Word
+
+-- | A value that can be used in a configuration file, or otherwise used to
+-- configure a program.
+--
+-- Unlike Show, there should only be instances of this type class for
+-- values that have a standard serialization that is understood outside of
+-- Haskell code.
+--
+-- When converting a type alias such as "type Foo = String" or "type Foo = Int"
+-- to a newtype, it's unsafe to derive a Show instance, because there may
+-- be code that shows the type to configure a value. Instead, define a
+-- ConfigurableValue instance.
+class ConfigurableValue t where
+	val :: t -> String
+
+-- | val String does not do any quoting, unlike show String
+instance ConfigurableValue String where
+	val = id
+
+instance ConfigurableValue Int where
+	val = show
+
+instance ConfigurableValue Integer where
+	val = show
+
+instance ConfigurableValue Float where
+	val = show
+
+instance ConfigurableValue Double where
+	val = show
+
+instance ConfigurableValue Word8 where
+	val = show
+
+instance ConfigurableValue Word16 where
+	val = show
+
+instance ConfigurableValue Word32 where
+	val = show
diff --git a/src/Propellor/Types/Dns.hs b/src/Propellor/Types/Dns.hs
--- a/src/Propellor/Types/Dns.hs
+++ b/src/Propellor/Types/Dns.hs
@@ -5,6 +5,7 @@
 import Propellor.Types.OS (HostName)
 import Propellor.Types.Empty
 import Propellor.Types.Info
+import Propellor.Types.ConfigurableValue
 
 import Data.Word
 import qualified Data.Map as M
@@ -19,9 +20,9 @@
 data IPAddr = IPv4 String | IPv6 String
 	deriving (Read, Show, Eq, Ord)
 
-fromIPAddr :: IPAddr -> String
-fromIPAddr (IPv4 addr) = addr
-fromIPAddr (IPv6 addr) = addr
+instance ConfigurableValue IPAddr where
+	val (IPv4 addr) = addr
+	val (IPv6 addr) = addr
 
 newtype AliasesInfo = AliasesInfo (S.Set HostName)
 	deriving (Show, Eq, Ord, Monoid, Typeable)
@@ -102,7 +103,7 @@
 
 reverseIP :: IPAddr -> ReverseIP
 reverseIP (IPv4 addr) = intercalate "." (reverse $ split "." addr) ++ ".in-addr.arpa"
-reverseIP addr@(IPv6 _) = reverse (intersperse '.' $ replace ":" "" $ fromIPAddr $ canonicalIP addr) ++ ".ip6.arpa"
+reverseIP addr@(IPv6 _) = reverse (intersperse '.' $ replace ":" "" $ val $ canonicalIP addr) ++ ".ip6.arpa"
 
 -- | Converts an IP address (particularly IPv6) to canonical, fully
 -- expanded form.
diff --git a/src/Propellor/Types/OS.hs b/src/Propellor/Types/OS.hs
--- a/src/Propellor/Types/OS.hs
+++ b/src/Propellor/Types/OS.hs
@@ -18,10 +18,11 @@
 	Group(..),
 	userGroup,
 	Port(..),
-	fromPort,
 	systemToTargetOS,
 ) where
 
+import Propellor.Types.ConfigurableValue
+
 import Network.BSD (HostName)
 import Data.Typeable
 import Data.String
@@ -75,10 +76,13 @@
 	fromString "9.3-RELEASE" = FBSD093
 	fromString _ = error "Invalid FreeBSD release"
 
+instance ConfigurableValue FBSDVersion where
+	val FBSD101 = "10.1-RELEASE"
+	val FBSD102 = "10.2-RELEASE"
+	val FBSD093 = "9.3-RELEASE"
+
 instance Show FBSDVersion where
-	show FBSD101 = "10.1-RELEASE"
-	show FBSD102 = "10.2-RELEASE"
-	show FBSD093 = "9.3-RELEASE"
+	show = val
 
 isStable :: DebianSuite -> Bool
 isStable (Stable _) = True
@@ -138,9 +142,15 @@
 newtype User = User UserName
 	deriving (Eq, Ord, Show)
 
+instance ConfigurableValue User where
+	val (User n) = n
+
 newtype Group = Group String
 	deriving (Eq, Ord, Show)
 
+instance ConfigurableValue Group where
+	val (Group n) = n
+
 -- | Makes a Group with the same name as the User.
 userGroup :: User -> Group
 userGroup (User u) = Group u
@@ -148,5 +158,5 @@
 newtype Port = Port Int
 	deriving (Eq, Ord, Show)
 
-fromPort :: Port -> String
-fromPort (Port p) = show p
+instance ConfigurableValue Port where
+	val (Port p) = show p
diff --git a/src/Propellor/Types/ZFS.hs b/src/Propellor/Types/ZFS.hs
--- a/src/Propellor/Types/ZFS.hs
+++ b/src/Propellor/Types/ZFS.hs
@@ -6,6 +6,8 @@
 
 module Propellor.Types.ZFS where
 
+import Propellor.Types.ConfigurableValue
+
 import Data.String
 import qualified Data.Set as Set
 import qualified Data.String.Utils as SU
@@ -32,24 +34,27 @@
 
 fromPropertyList :: [(String, String)] -> ZFSProperties
 fromPropertyList props =
-  Set.fromList $ map fromPair props
+	Set.fromList $ map fromPair props
 
 zfsName :: ZFS -> String
 zfsName (ZFS (ZPool pool) dataset) = intercalate "/" [pool, show dataset]
 
+instance ConfigurableValue ZDataset where
+	val (ZDataset paths) = intercalate "/" paths
+
 instance Show ZDataset where
-  show (ZDataset paths) = intercalate "/" paths
+	show = val
 
 instance IsString ZDataset where
-  fromString s = ZDataset $ SU.split "/" s
+	fromString s = ZDataset $ SU.split "/" s
 
 instance IsString ZPool where
-  fromString p = ZPool p
+	fromString p = ZPool p
 
 class Value a where
-  toValue :: a -> String
-  fromValue :: (IsString a) => String -> a
-  fromValue = fromString
+	toValue :: a -> String
+	fromValue :: (IsString a) => String -> a
+	fromValue = fromString
 
 data ZFSYesNo = ZFSYesNo Bool deriving (Show, Eq, Ord)
 data ZFSOnOff = ZFSOnOff Bool deriving (Show, Eq, Ord)
@@ -57,57 +62,57 @@
 data ZFSString = ZFSString String deriving (Show, Eq, Ord)
 
 instance Value ZFSYesNo where
-  toValue (ZFSYesNo True) = "yes"
-  toValue (ZFSYesNo False) = "no"
+	toValue (ZFSYesNo True) = "yes"
+	toValue (ZFSYesNo False) = "no"
 
 instance Value ZFSOnOff where
-  toValue (ZFSOnOff True) = "on"
-  toValue (ZFSOnOff False) = "off"
+	toValue (ZFSOnOff True) = "on"
+	toValue (ZFSOnOff False) = "off"
 
 instance Value ZFSSize where
-  toValue (ZFSSize s) = show s
+	toValue (ZFSSize s) = show s
 
 instance Value ZFSString where
-  toValue (ZFSString s) = s
+	toValue (ZFSString s) = s
 
 instance IsString ZFSString where
-  fromString = ZFSString
+	fromString = ZFSString
 
 instance IsString ZFSYesNo where
-  fromString "yes" = ZFSYesNo True
-  fromString "no" = ZFSYesNo False
-  fromString _ = error "Not yes or no"
+	fromString "yes" = ZFSYesNo True
+	fromString "no" = ZFSYesNo False
+	fromString _ = error "Not yes or no"
 
 instance IsString ZFSOnOff where
-  fromString "on" = ZFSOnOff True
-  fromString "off" = ZFSOnOff False
-  fromString _ = error "Not on or off"
+	fromString "on" = ZFSOnOff True
+	fromString "off" = ZFSOnOff False
+	fromString _ = error "Not on or off"
 
 data ZFSACLInherit = AIDiscard | AINoAllow | AISecure | AIPassthrough deriving (Show, Eq, Ord)
 instance IsString ZFSACLInherit where
-  fromString "discard" = AIDiscard
-  fromString "noallow" = AINoAllow
-  fromString "secure" = AISecure
-  fromString "passthrough" = AIPassthrough
-  fromString _ = error "Not valid aclpassthrough value"
+	fromString "discard" = AIDiscard
+	fromString "noallow" = AINoAllow
+	fromString "secure" = AISecure
+	fromString "passthrough" = AIPassthrough
+	fromString _ = error "Not valid aclpassthrough value"
 
 instance Value ZFSACLInherit where
-  toValue AIDiscard = "discard"
-  toValue AINoAllow = "noallow"
-  toValue AISecure = "secure"
-  toValue AIPassthrough = "passthrough"
+	toValue AIDiscard = "discard"
+	toValue AINoAllow = "noallow"
+	toValue AISecure = "secure"
+	toValue AIPassthrough = "passthrough"
 
 data ZFSACLMode = AMDiscard | AMGroupmask | AMPassthrough deriving (Show, Eq, Ord)
 instance IsString ZFSACLMode where
-  fromString "discard" = AMDiscard
-  fromString "groupmask" = AMGroupmask
-  fromString "passthrough" = AMPassthrough
-  fromString _ = error "Invalid zfsaclmode"
+	fromString "discard" = AMDiscard
+	fromString "groupmask" = AMGroupmask
+	fromString "passthrough" = AMPassthrough
+	fromString _ = error "Invalid zfsaclmode"
 
 instance Value ZFSACLMode where
-  toValue AMDiscard = "discard"
-  toValue AMGroupmask = "groupmask"
-  toValue AMPassthrough = "passthrough"
+	toValue AMDiscard = "discard"
+	toValue AMGroupmask = "groupmask"
+	toValue AMPassthrough = "passthrough"
 
 data ZFSProperty = Mounted ZFSYesNo
 	       | Mountpoint ZFSString