From 2ba4b6fb3d29b2b65aa60f4bd591ed8cf6a63e27 Mon Sep 17 00:00:00 2001
From: Joey Hess <joeyh@joeyh.name>
Date: Sun, 26 Feb 2017 15:27:22 -0400
Subject: Added ConfigurableValue type class

* 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.

This was motivated by the bug caused by type Port = Int changing to
newtype Port = Port Int deriving Show
After that change, some things that used show port to generate config
files were broken. By using the ConfigurableValue type class instead,
such breakage can be prevented.
---
 src/Propellor/Property/Docker.hs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'src/Propellor/Property/Docker.hs')

diff --git a/src/Propellor/Property/Docker.hs b/src/Propellor/Property/Docker.hs
index 0bfcc781..68fa2926 100644
--- a/src/Propellor/Property/Docker.hs
+++ b/src/Propellor/Property/Docker.hs
@@ -660,10 +660,10 @@ listImages :: IO [ImageUID]
 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 $
-- 
cgit v1.3-2-g0d8e


From 55ed8e8743e861e2230e40670a56034353cf4e32 Mon Sep 17 00:00:00 2001
From: Joey Hess <joeyh@joeyh.name>
Date: Sun, 26 Feb 2017 16:11:38 -0400
Subject: use ConfigurableValue where applicable

* Removed fromPort (use val instead). (API change)
* Removed several Show instances that were only used for generating
  configuration, replacing with ConfigurableValue instances. (API change)

It's somewhat annoying that IsInfo requires a Show instance.
That's needed to be able to display Info in ghci, but some non-derived Show
instances had to be kept to support that.
---
 debian/changelog                            |  5 ++++-
 src/Propellor/Property/Apache.hs            | 10 +++++-----
 src/Propellor/Property/Apt/PPA.hs           | 27 +++++++++++++--------------
 src/Propellor/Property/Docker.hs            |  2 +-
 src/Propellor/Property/Firewall.hs          |  6 +++---
 src/Propellor/Property/FreeBSD/Poudriere.hs | 12 +++++++-----
 src/Propellor/Property/Logcheck.hs          | 12 ++++++------
 src/Propellor/Property/Munin.hs             |  2 +-
 src/Propellor/Property/OpenId.hs            |  2 +-
 src/Propellor/Property/Sbuild.hs            | 28 ++++++++++++++--------------
 src/Propellor/Property/Ssh.hs               |  2 +-
 src/Propellor/Property/Systemd.hs           |  2 +-
 src/Propellor/Property/Tor.hs               |  4 ++--
 src/Propellor/Types/OS.hs                   | 16 ++++++++++------
 src/Propellor/Types/ZFS.hs                  |  7 ++++++-
 15 files changed, 75 insertions(+), 62 deletions(-)

(limited to 'src/Propellor/Property/Docker.hs')

diff --git a/debian/changelog b/debian/changelog
index bbcf7bdc..e3009188 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,8 +1,11 @@
-propellor (3.3.2) UNRELEASED; urgency=medium
+propellor (3.4.0) UNRELEASED; 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 (use val instead). (API change)
+  * Removed several Show instances that were only used for generating
+    configuration, replacing with ConfigurableValue instances. (API change)
 
  -- Joey Hess <id@joeyh.name>  Sun, 26 Feb 2017 15:15:33 -0400
 
diff --git a/src/Propellor/Property/Apache.hs b/src/Propellor/Property/Apache.hs
index f321143f..d912acc1 100644
--- a/src/Propellor/Property/Apache.hs
+++ b/src/Propellor/Property/Apache.hs
@@ -72,7 +72,7 @@ listenPorts :: [Port] -> Property DebianLike
 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 @@ virtualHost domain port docroot = virtualHost' domain port docroot []
 -- | 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 @@ httpsVirtualHost' domain docroot letos addedcfg = setup <!> teardown
 			]
 	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/PPA.hs b/src/Propellor/Property/Apt/PPA.hs
index 49fa9fa7..346125ff 100644
--- a/src/Propellor/Property/Apt/PPA.hs
+++ b/src/Propellor/Property/Apt/PPA.hs
@@ -25,8 +25,8 @@ data PPA = PPA
 	, 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 @@ instance IsString PPA where
 -- | 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 @@ data AptKeyId = AptKeyId
 	, 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 @@ addKeyId keyId =
 			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 @@ data AptSource = AptSource
 	, 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 :: AptRepository -> Property DebianLike
 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 @@ addRepository (AptRepositorySource src) =
 		. 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/Docker.hs b/src/Propellor/Property/Docker.hs
index 68fa2926..d2b2ee35 100644
--- a/src/Propellor/Property/Docker.hs
+++ b/src/Propellor/Property/Docker.hs
@@ -323,7 +323,7 @@ class Publishable p where
 	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
diff --git a/src/Propellor/Property/Firewall.hs b/src/Propellor/Property/Firewall.hs
index 3ea19ffa..ce08cc06 100644
--- a/src/Propellor/Property/Firewall.hs
+++ b/src/Propellor/Property/Firewall.hs
@@ -51,9 +51,9 @@ toIpTable r =  map Param $
 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) =
@@ -100,7 +100,7 @@ toIpTableArg (NotDestination ipwm) =
 	]
 toIpTableArg (NatDestination ip mport) =
 	[ "--to-destination"
-	, fromIPAddr ip ++ maybe "" (\p -> ":" ++ fromPort p) mport
+	, fromIPAddr ip ++ maybe "" (\p -> ":" ++ val p) mport
 	]
 toIpTableArg (r :- r') = toIpTableArg r <> toIpTableArg r'
 
diff --git a/src/Propellor/Property/FreeBSD/Poudriere.hs b/src/Propellor/Property/FreeBSD/Poudriere.hs
index 58477468..e6ddea16 100644
--- a/src/Propellor/Property/FreeBSD/Poudriere.hs
+++ b/src/Propellor/Property/FreeBSD/Poudriere.hs
@@ -19,6 +19,7 @@ poudriereConfigPath = "/usr/local/etc/poudriere.conf"
 
 newtype PoudriereConfigured = PoudriereConfigured String
 	deriving (Typeable, Monoid, Show)
+
 instance IsInfo PoudriereConfigured where
 	propagateInfo _ = False
 
@@ -68,7 +69,7 @@ jail j@(Jail name version arch) = tightenTargets $
 			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
@@ -101,9 +102,10 @@ data PoudriereZFS = PoudriereZFS ZFS.ZFS ZFS.ZFSProperties
 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
@@ -127,7 +129,7 @@ instance ToShellConfigLines PoudriereZFS where
 	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/Logcheck.hs b/src/Propellor/Property/Logcheck.hs
index ced9fce2..8eaf56fd 100644
--- a/src/Propellor/Property/Logcheck.hs
+++ b/src/Propellor/Property/Logcheck.hs
@@ -16,21 +16,21 @@ import qualified Propellor.Property.File as File
 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/Munin.hs b/src/Propellor/Property/Munin.hs
index dd74d91b..13c72f3a 100644
--- a/src/Propellor/Property/Munin.hs
+++ b/src/Propellor/Property/Munin.hs
@@ -47,7 +47,7 @@ hostListFragment' hs os = concatMap muninHost hs
 	muninHost :: Host -> [String]
 	muninHost h = [ "[" ++ (hostName h) ++ "]"
 		      , "  address " ++ maybe (hostName h) (fromIPAddr . fst) (hOverride h)
-		      ] ++ (maybe [] (\x -> ["  port " ++ (fromPort $ snd x)]) (hOverride h)) ++ [""]
+		      ] ++ (maybe [] (\x -> ["  port " ++ (val $ snd x)]) (hOverride h)) ++ [""]
 	hOverride :: Host -> Maybe (IPAddr, Port)
 	hOverride h = lookup (hostName h) os
 
diff --git a/src/Propellor/Property/OpenId.hs b/src/Propellor/Property/OpenId.hs
index 0abf38a6..00daa57d 100644
--- a/src/Propellor/Property/OpenId.hs
+++ b/src/Propellor/Property/OpenId.hs
@@ -28,7 +28,7 @@ providerFor users hn mp = propertyList desc $ props
   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/Sbuild.hs b/src/Propellor/Property/Sbuild.hs
index db5982cd..aaa83e6f 100644
--- a/src/Propellor/Property/Sbuild.hs
+++ b/src/Propellor/Property/Sbuild.hs
@@ -111,8 +111,8 @@ type Suite = String
 -- 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 @@ built s@(SbuildSchroot suite arch) mirror cc =
   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 <$>
@@ -170,18 +170,18 @@ built s@(SbuildSchroot suite arch) mirror cc =
 	-- TODO we should kill any sessions still using the chroot
 	-- before destroying it (as suggested by sbuild-destroychroot)
 	deleted = check (not <$> 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 @@ built s@(SbuildSchroot suite arch) mirror cc =
 			then ensureProperty w $
 				ConfFile.containsIniSetting
 					(schrootConf s)
-					( show s ++ "-sbuild"
+					( val s ++ "-sbuild"
 					, "aliases"
 					, aliases
 					)
@@ -263,7 +263,7 @@ updatedFor system = property' ("updated sbuild schroot for " ++ show system) $
 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 @@ updated s@(SbuildSchroot suite arch) =
 -- 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 @@ piupartsConf s@(SbuildSchroot _ arch) =
 
 	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/Ssh.hs b/src/Propellor/Property/Ssh.hs
index 322cddef..828601b8 100644
--- a/src/Propellor/Property/Ssh.hs
+++ b/src/Propellor/Property/Ssh.hs
@@ -120,7 +120,7 @@ dotFile f user = do
 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
index 78529f73..e1e20974 100644
--- a/src/Propellor/Property/Systemd.hs
+++ b/src/Propellor/Property/Systemd.hs
@@ -421,7 +421,7 @@ class Publishable a where
 	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
index 72bd45f5..24d5b687 100644
--- a/src/Propellor/Property/Tor.hs
+++ b/src/Propellor/Property/Tor.hs
@@ -128,7 +128,7 @@ hiddenService hn port = hiddenService' hn [port]
 
 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 @@ hiddenService' hn ports = ConfFile.adjustSection
 	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/Types/OS.hs b/src/Propellor/Types/OS.hs
index 696c36b0..8d7f1ba3 100644
--- a/src/Propellor/Types/OS.hs
+++ b/src/Propellor/Types/OS.hs
@@ -18,10 +18,11 @@ module Propellor.Types.OS (
 	Group(..),
 	userGroup,
 	Port(..),
-	fromPort,
 	systemToTargetOS,
 ) where
 
+import Propellor.Types.ConfigurableValue
+
 import Network.BSD (HostName)
 import Data.Typeable
 import Data.String
@@ -75,10 +76,13 @@ instance IsString FBSDVersion where
 	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
@@ -148,5 +152,5 @@ userGroup (User u) = Group u
 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
index 3ce4b22c..42ff74ec 100644
--- 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
@@ -37,8 +39,11 @@ fromPropertyList 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
-- 
cgit v1.3-2-g0d8e