remove Read instance for Ref

Removed instance, got it all to build using fromRef. (With a few things
that really need to show something using a ref for debugging stubbed out.)

Then added back Read instance, and made Logs.View use it for serialization.
This changes the view log format.

Annex/Branch.hs

@@ -58,11 +58,11 @@ name = Git.Ref "git-annex"
 
 {- Fully qualified name of the branch. -}
 fullname :: Git.Ref
-fullname = Git.Ref $ "refs/heads/" ++ show name
+fullname = Git.Ref $ "refs/heads/" ++ fromRef name
 
 {- Branch's name in origin. -}
 originname :: Git.Ref
-originname = Git.Ref $ "origin/" ++ show name
+originname = Git.Ref $ "origin/" ++ fromRef name
 
 {- Does origin/git-annex exist? -}
 hasOrigin :: Annex Bool
@@ -87,8 +87,8 @@ getBranch = maybe (hasOrigin >>= go >>= use) return =<< branchsha
   where
 	go True = do
 		inRepo $ Git.Command.run
-			[Param "branch", Param $ show name, Param $ show originname]
-		fromMaybe (error $ "failed to create " ++ show name)
+			[Param "branch", Param $ fromRef name, Param $ fromRef originname]
+		fromMaybe (error $ "failed to create " ++ fromRef name)
 			<$> branchsha
 	go False = withIndex' True $
 		inRepo $ Git.Branch.commitAlways "branch created" fullname []
@@ -154,7 +154,7 @@ updateTo pairs = do
 			then "update"
 			else "merging " ++
 				unwords (map Git.Ref.describe branches) ++ 
-				" into " ++ show name
+				" into " ++ fromRef name
 		localtransitions <- parseTransitionsStrictly "local"
 			<$> getLocal transitionsLog
 		unless (null branches) $ do
@@ -291,7 +291,7 @@ files = do
 branchFiles :: Annex [FilePath]
 branchFiles = withIndex $ inRepo $ Git.Command.pipeNullSplitZombie
 	[ Params "ls-tree --name-only -r -z"
-	, Param $ show fullname
+	, Param $ fromRef fullname
 	]
 
 {- Populates the branch's index file with the current branch contents.
@@ -368,7 +368,7 @@ needUpdateIndex branchref = do
 setIndexSha :: Git.Ref -> Annex ()
 setIndexSha ref = do
 	f <- fromRepo gitAnnexIndexStatus
-	liftIO $ writeFile f $ show ref ++ "\n"
+	liftIO $ writeFile f $ fromRef ref ++ "\n"
 	setAnnexFilePerm f
 
 {- Stages the journal into the index and returns an action that will
@@ -442,7 +442,7 @@ ignoreRefs rs = do
 	let s = S.unions [old, S.fromList rs]
 	f <- fromRepo gitAnnexIgnoredRefs
 	replaceFile f $ \tmp -> liftIO $ writeFile tmp $
-		unlines $ map show $ S.elems s
+		unlines $ map fromRef $ S.elems s
 
 getIgnoredRefs :: Annex (S.Set Git.Ref)
 getIgnoredRefs = S.fromList . mapMaybe Git.Sha.extractSha . lines <$> content

Annex/Direct.hs

@@ -286,18 +286,18 @@ setDirect wantdirect = do
  - this way things that show HEAD (eg shell prompts) will
  - hopefully show just "master". -}
 directBranch :: Ref -> Ref
-directBranch orighead = case split "/" $ show orighead of
+directBranch orighead = case split "/" $ fromRef orighead of
 	("refs":"heads":"annex":"direct":_) -> orighead
 	("refs":"heads":rest) ->
 		Ref $ "refs/heads/annex/direct/" ++ intercalate "/" rest
-	_ -> Ref $ "refs/heads/" ++ show (Git.Ref.base orighead)
+	_ -> Ref $ "refs/heads/" ++ fromRef (Git.Ref.base orighead)
 
 {- Converts a directBranch back to the original branch.
  -
  - Any other ref is left unchanged.
  -}
 fromDirectBranch :: Ref -> Ref
-fromDirectBranch directhead = case split "/" $ show directhead of
+fromDirectBranch directhead = case split "/" $ fromRef directhead of
 	("refs":"heads":"annex":"direct":rest) -> 
 		Ref $ "refs/heads/" ++ intercalate "/" rest
 	_ -> directhead

Annex/TaggedPush.hs

@@ -35,11 +35,11 @@ toTaggedBranch u info b = Git.Ref $ intercalate "/" $ catMaybes
 	[ Just "refs/synced"
 	, Just $ fromUUID u
 	, toB64 <$> info
-	, Just $ show $ Git.Ref.base b
+	, Just $ Git.fromRef $ Git.Ref.base b
 	]
 
 fromTaggedBranch :: Git.Branch -> Maybe (UUID, Maybe String)
-fromTaggedBranch b = case split "/" $ show b of
+fromTaggedBranch b = case split "/" $ Git.fromRef b of
 	("refs":"synced":u:info:_base) ->
 		Just (toUUID u, fromB64Maybe info)
 	("refs":"synced":u:_base) ->
@@ -58,4 +58,4 @@ taggedPush u info branch remote = Git.Command.runBool
         , Param $ refspec branch
         ]
   where
-	refspec b = show b ++ ":" ++ show (toTaggedBranch u info b)
+	refspec b = Git.fromRef b ++ ":" ++ Git.fromRef (toTaggedBranch u info b)

Annex/View.hs

@@ -310,7 +310,7 @@ genViewBranch :: View -> Annex () -> Annex Git.Branch
 genViewBranch view a = withIndex $ do
 	a
 	let branch = branchView view
-	void $ inRepo $ Git.Branch.commit True (show branch) branch []
+	void $ inRepo $ Git.Branch.commit True (fromRef branch) branch []
 	return branch
 
 {- Runs an action using the view index file.

Assistant/Threads/Merger.hs

@@ -80,8 +80,8 @@ onChange file
 	mergecurrent (Just current)
 		| equivBranches changedbranch current = do
 			debug
-				[ "merging", show changedbranch
-				, "into", show current
+				[ "merging", Git.fromRef changedbranch
+				, "into", Git.fromRef current
 				]
 			void $ liftAnnex  $ Command.Sync.mergeFrom changedbranch
 	mergecurrent _ = noop
@@ -105,12 +105,12 @@ onChange file
 equivBranches :: Git.Ref -> Git.Ref -> Bool
 equivBranches x y = base x == base y
   where
-	base = takeFileName . show
+	base = takeFileName . Git.fromRef
 
 isAnnexBranch :: FilePath -> Bool
 isAnnexBranch f = n `isSuffixOf` f
   where
-	n = '/' : show Annex.Branch.name
+	n = '/' : Git.fromRef Annex.Branch.name
 
 fileToBranch :: FilePath -> Git.Ref
 fileToBranch f = Git.Ref $ "refs" </> base

Assistant/Types/NetMessager.hs

@@ -32,7 +32,7 @@ data NetMessage
 	| PairingNotification PairStage ClientID UUID
 	-- used for git push over the network messager
 	| Pushing ClientID PushStage
-	deriving (Show, Eq, Ord)
+	deriving (Eq, Ord, Show)
 
 {- Something used to identify the client, or clients to send the message to. -}
 type ClientID = Text
@@ -50,7 +50,7 @@ data PushStage
 	| SendPackOutput SequenceNum ByteString
 	-- sent when git receive-pack exits, with its exit code
 	| ReceivePackDone ExitCode
-	deriving (Show, Eq, Ord)
+	deriving (Eq, Ord, Show)
 
 {- A sequence number. Incremented by one per packet in a sequence,
  - starting with 1 for the first packet. 0 means sequence numbers are

Assistant/XMPP.hs

@@ -13,6 +13,7 @@ import Assistant.Common
 import Assistant.Types.NetMessager
 import Assistant.Pairing
 import Git.Sha (extractSha)
+import Git
 
 import Network.Protocol.XMPP hiding (Node)
 import Data.Text (Text)
@@ -152,7 +153,7 @@ pushMessage = gitAnnexMessage . encode
   where
 	encode (CanPush u shas) =
 		gitAnnexTag canPushAttr $ T.pack $ unwords $
-			fromUUID u : map show shas
+			fromUUID u : map fromRef shas
 	encode (PushRequest u) =
 		gitAnnexTag pushRequestAttr $ T.pack $ fromUUID u
 	encode (StartingPush u) =

Command/Log.hs

@@ -140,7 +140,7 @@ getLog key os = do
 		[ Params "log -z --pretty=format:%ct --raw --abbrev=40"
 		, Param "--remove-empty"
 		] ++ os ++
-		[ Param $ show Annex.Branch.fullname
+		[ Param $ Git.fromRef Annex.Branch.fullname
 		, Param "--"
 		, Param logfile
 		]

Command/Repair.hs

@@ -81,4 +81,4 @@ trackingOrSyncBranch :: Ref -> Bool
 trackingOrSyncBranch b = Git.Repair.isTrackingBranch b || isAnnexSyncBranch b
 
 isAnnexSyncBranch :: Ref -> Bool
-isAnnexSyncBranch b = "refs/synced/" `isPrefixOf` show b
+isAnnexSyncBranch b = "refs/synced/" `isPrefixOf` fromRef b

Command/Sync.hs

@@ -192,12 +192,12 @@ pushLocal (Just branch) = do
 
 updateBranch :: Git.Ref -> Git.Repo -> IO ()
 updateBranch syncbranch g = 
-	unlessM go $ error $ "failed to update " ++ show syncbranch
+	unlessM go $ error $ "failed to update " ++ Git.fromRef syncbranch
   where
 	go = Git.Command.runBool
 		[ Param "branch"
 		, Param "-f"
-		, Param $ show $ Git.Ref.base syncbranch
+		, Param $ Git.fromRef $ Git.Ref.base syncbranch
 		] g
 
 pullRemote :: Remote -> Maybe Git.Ref -> CommandStart
@@ -283,15 +283,15 @@ pushBranch remote branch g = tryIO (directpush g) `after` syncpush g
 		, refspec branch
 		]
 	directpush = Git.Command.runQuiet $ pushparams
-		[show $ Git.Ref.base $ fromDirectBranch branch]
+		[Git.fromRef $ Git.Ref.base $ fromDirectBranch branch]
 	pushparams branches =
 		[ Param "push"
 		, Param $ Remote.name remote
 		] ++ map Param branches
 	refspec b = concat 
-		[ show $ Git.Ref.base b
+		[ Git.fromRef $ Git.Ref.base b
 		,  ":"
-		, show $ Git.Ref.base $ syncBranch b
+		, Git.fromRef $ Git.Ref.base $ syncBranch b
 		]
 
 commitAnnex :: CommandStart

Command/Uninit.hs

@@ -24,7 +24,7 @@ check :: Annex ()
 check = do
 	b <- current_branch
 	when (b == Annex.Branch.name) $ error $
-		"cannot uninit when the " ++ show b ++ " branch is checked out"
+		"cannot uninit when the " ++ Git.fromRef b ++ " branch is checked out"
 	top <- fromRepo Git.repoPath
 	cwd <- liftIO getCurrentDirectory
 	whenM ((/=) <$> liftIO (absPath top) <*> liftIO (absPath cwd)) $
@@ -77,7 +77,7 @@ finish = do
 	-- avoid normal shutdown
 	saveState False
 	inRepo $ Git.Command.run
-		[Param "branch", Param "-D", Param $ show Annex.Branch.name]
+		[Param "branch", Param "-D", Param $ Git.fromRef Annex.Branch.name]
 	liftIO exitSuccess
 
 {- Keys that were moved out of the annex have a hard link still in the

Command/Unused.hs

@@ -266,7 +266,7 @@ withKeysReferencedInGit a = do
 		map (separate (== ' ')) .
 		lines
 	nubRefs = map (Git.Ref . snd) . nubBy (\(x, _) (y, _) -> x == y)
-	ourbranchend = '/' : show Annex.Branch.name
+	ourbranchend = '/' : Git.fromRef Annex.Branch.name
 	ourbranches (_, b) = not (ourbranchend `isSuffixOf` b)
 		&& not ("refs/synced/" `isPrefixOf` b)
 	addHead headRef refs = case headRef of

Command/VPop.hs

@@ -9,6 +9,7 @@ module Command.VPop where
 
 import Common.Annex
 import Command
+import qualified Git
 import qualified Git.Command
 import qualified Git.Ref
 import Types.View
@@ -41,7 +42,7 @@ start ps = go =<< currentView
 				showOutput
 				inRepo $ Git.Command.runBool
 					[ Param "checkout"
-					, Param $ show $ Git.Ref.base $
+					, Param $ Git.fromRef $ Git.Ref.base $
 						viewParentBranch v
 					]
 	sameparentbranch a b = viewParentBranch a == viewParentBranch b

Command/View.hs

@@ -73,7 +73,7 @@ checkoutViewBranch view mkbranch = do
 	showOutput
 	ok <- inRepo $ Git.Command.runBool
 		[ Param "checkout"
-		, Param (show $ Git.Ref.base branch)
+		, Param (Git.fromRef $ Git.Ref.base branch)
 		]
 	when ok $ do
 		setView view

Git.hs

@@ -13,6 +13,7 @@
 module Git (
 	Repo(..),
 	Ref(..),
+	fromRef,
 	Branch,
 	Sha,
 	Tag,

Git/Branch.hs

@@ -28,7 +28,7 @@ current r = do
 	case v of
 		Nothing -> return Nothing
 		Just branch -> 
-			ifM (null <$> pipeReadStrict [Param "show-ref", Param $ show branch] r)
+			ifM (null <$> pipeReadStrict [Param "show-ref", Param $ fromRef branch] r)
 				( return Nothing
 				, return v
 				)
@@ -36,7 +36,7 @@ current r = do
 {- The current branch, which may not really exist yet. -}
 currentUnsafe :: Repo -> IO (Maybe Git.Ref)
 currentUnsafe r = parse . firstLine
-	<$> pipeReadStrict [Param "symbolic-ref", Param $ show Git.Ref.headRef] r
+	<$> pipeReadStrict [Param "symbolic-ref", Param $ fromRef Git.Ref.headRef] r
   where
 	parse l
 		| null l = Nothing
@@ -51,7 +51,7 @@ changed origbranch newbranch repo
   where
 	diffs = pipeReadStrict
 		[ Param "log"
-		, Param (show origbranch ++ ".." ++ show newbranch)
+		, Param (fromRef origbranch ++ ".." ++ fromRef newbranch)
 		, Params "--oneline -n1"
 		] repo
 
@@ -74,7 +74,7 @@ fastForward branch (first:rest) repo =
   where
 	no_ff = return False
 	do_ff to = do
-		run [Param "update-ref", Param $ show branch, Param $ show to] repo
+		run [Param "update-ref", Param $ fromRef branch, Param $ fromRef to] repo
 		return True
 	findbest c [] = return $ Just c
 	findbest c (r:rs)
@@ -104,14 +104,14 @@ commit allowempty message branch parentrefs repo = do
 	ifM (cancommit tree)
 		( do
 			sha <- getSha "commit-tree" $ pipeWriteRead
-				(map Param $ ["commit-tree", show tree] ++ ps)
+				(map Param $ ["commit-tree", fromRef tree] ++ ps)
 				(Just $ flip hPutStr message) repo
 			update branch sha repo
 			return $ Just sha
 		, return Nothing
 		)
   where
-	ps = concatMap (\r -> ["-p", show r]) parentrefs
+	ps = concatMap (\r -> ["-p", fromRef r]) parentrefs
 	cancommit tree
 		| allowempty = return True
 		| otherwise = case parentrefs of
@@ -130,8 +130,8 @@ forcePush b = "+" ++ b
 update :: Branch -> Sha -> Repo -> IO ()
 update branch sha = run 
 	[ Param "update-ref"
-	, Param $ show branch
-	, Param $ show sha
+	, Param $ fromRef branch
+	, Param $ fromRef sha
 	]
 
 {- Checks out a branch, creating it if necessary. -}
@@ -140,7 +140,7 @@ checkout branch = run
 	[ Param "checkout"
 	, Param "-q"
 	, Param "-B"
-	, Param $ show $ Git.Ref.base branch
+	, Param $ fromRef $ Git.Ref.base branch
 	]
 
 {- Removes a branch. -}
@@ -149,5 +149,5 @@ delete branch = run
 	[ Param "branch"
 	, Param "-q"
 	, Param "-D"
-	, Param $ show $ Git.Ref.base branch
+	, Param $ fromRef $ Git.Ref.base branch
 	]

Git/CatFile.hs

@@ -50,7 +50,7 @@ catFileStop (CatFileHandle p _) = CoProcess.stop p
 {- Reads a file from a specified branch. -}
 catFile :: CatFileHandle -> Branch -> FilePath -> IO L.ByteString
 catFile h branch file = catObject h $ Ref $
-	show branch ++ ":" ++ toInternalGitPath file
+	fromRef branch ++ ":" ++ toInternalGitPath file
 
 {- Uses a running git cat-file read the content of an object.
  - Objects that do not exist will have "" returned. -}
@@ -60,7 +60,7 @@ catObject h object = maybe L.empty fst3 <$> catObjectDetails h object
 catObjectDetails :: CatFileHandle -> Ref -> IO (Maybe (L.ByteString, Sha, ObjectType))
 catObjectDetails (CatFileHandle hdl _) object = CoProcess.query hdl send receive
   where
-	query = show object
+	query = fromRef object
 	send to = hPutStrLn to query
 	receive from = do
 		header <- hGetLine from
@@ -72,8 +72,8 @@ catObjectDetails (CatFileHandle hdl _) object = CoProcess.query hdl send receive
 						_ -> dne
 				| otherwise -> dne
 			_
-				| header == show object ++ " missing" -> dne
-				| otherwise -> error $ "unknown response from git cat-file " ++ show (header, object)
+				| header == fromRef object ++ " missing" -> dne
+				| otherwise -> error $ "unknown response from git cat-file " ++ show (header, query)
 	readcontent objtype bytes from sha = do
 		content <- S.hGet from bytes
 		eatchar '\n' from

Git/DiffTree.hs

@@ -36,12 +36,12 @@ data DiffTreeItem = DiffTreeItem
 {- Diffs two tree Refs. -}
 diffTree :: Ref -> Ref -> Repo -> IO ([DiffTreeItem], IO Bool)
 diffTree src dst = getdiff (Param "diff-tree")
-	[Param (show src), Param (show dst)]
+	[Param (fromRef src), Param (fromRef dst)]
 
 {- Diffs two tree Refs, recursing into sub-trees -}
 diffTreeRecursive :: Ref -> Ref -> Repo -> IO ([DiffTreeItem], IO Bool)
 diffTreeRecursive src dst = getdiff (Param "diff-tree")
-	[Param "-r", Param (show src), Param (show dst)]
+	[Param "-r", Param (fromRef src), Param (fromRef dst)]
 
 {- Diffs between a tree and the index. Does nothing if there is not yet a
  - commit in the repository. -}
@@ -61,7 +61,7 @@ diffIndex' :: Ref -> [CommandParam] -> Repo -> IO ([DiffTreeItem], IO Bool)
 diffIndex' ref params repo =
 	ifM (Git.Ref.headExists repo)
 		( getdiff (Param "diff-index")
-			( params ++ [Param $ show ref] )
+			( params ++ [Param $ fromRef ref] )
 			repo
 		, return ([], return True)
 		)

Git/Fsck.hs

@@ -74,7 +74,7 @@ isMissing s r = either (const True) (const False) <$> tryIO dump
   where
 	dump = runQuiet
 		[ Param "show"
-		, Param (show s)
+		, Param (fromRef s)
 		] r
 
 findShas :: Bool -> String -> [Sha]

Git/LsTree.hs

@@ -38,13 +38,13 @@ lsTree t repo = map parseLsTree
 	<$> pipeNullSplitZombie (lsTreeParams t) repo
 
 lsTreeParams :: Ref -> [CommandParam]
-lsTreeParams t = [ Params "ls-tree --full-tree -z -r --", File $ show t ]
+lsTreeParams t = [ Params "ls-tree --full-tree -z -r --", File $ fromRef t ]
 
 {- Lists specified files in a tree. -}
 lsTreeFiles :: Ref -> [FilePath] -> Repo -> IO [TreeItem]
 lsTreeFiles t fs repo = map parseLsTree <$> pipeNullSplitStrict ps repo
   where
-  	ps = [Params "ls-tree --full-tree -z --", File $ show t] ++ map File fs
+  	ps = [Params "ls-tree --full-tree -z --", File $ fromRef t] ++ map File fs
 
 {- Parses a line of ls-tree output.
  - (The --long format is not currently supported.) -}

Git/Merge.hs

@@ -15,7 +15,7 @@ import Git.BuildVersion
 {- Avoids recent git's interactive merge. -}
 mergeNonInteractive :: Ref -> Repo -> IO Bool
 mergeNonInteractive branch
-	| older "1.7.7.6" = merge [Param $ show branch]
-	| otherwise = merge [Param "--no-edit", Param $ show branch]
+	| older "1.7.7.6" = merge [Param $ fromRef branch]
+	| otherwise = merge [Param "--no-edit", Param $ fromRef branch]
   where
 	merge ps = runBool $ Param "merge" : ps

Git/Objects.hs

@@ -32,4 +32,4 @@ listLooseObjectShas r = catchDefaultIO [] $
 looseObjectFile :: Repo -> Sha -> FilePath
 looseObjectFile r sha = objectsDir r </> prefix </> rest
   where
-	(prefix, rest) = splitAt 2 (show sha)
+	(prefix, rest) = splitAt 2 (fromRef sha)

Git/Ref.hs

@@ -20,12 +20,12 @@ headRef = Ref "HEAD"
 
 {- Converts a fully qualified git ref into a user-visible string. -}
 describe :: Ref -> String
-describe = show . base
+describe = fromRef . base
 
 {- Often git refs are fully qualified (eg: refs/heads/master).
  - Converts such a fully qualified ref into a base ref (eg: master). -}
 base :: Ref -> Ref
-base = Ref . remove "refs/heads/" . remove "refs/remotes/" . show
+base = Ref . remove "refs/heads/" . remove "refs/remotes/" . fromRef
   where
 	remove prefix s
 		| prefix `isPrefixOf` s = drop (length prefix) s
@@ -35,13 +35,13 @@ base = Ref . remove "refs/heads/" . remove "refs/remotes/" . show
  - it under the directory. -}
 under :: String -> Ref -> Ref
 under dir r = Ref $ dir ++ "/" ++
-	(reverse $ takeWhile (/= '/') $ reverse $ show r)
+	(reverse $ takeWhile (/= '/') $ reverse $ fromRef r)
 
 {- Given a directory such as "refs/remotes/origin", and a ref such as
  - refs/heads/master, yields a version of that ref under the directory,
  - such as refs/remotes/origin/master. -}
 underBase :: String -> Ref -> Ref
-underBase dir r = Ref $ dir ++ "/" ++ show (base r)
+underBase dir r = Ref $ dir ++ "/" ++ fromRef (base r)
 
 {- A Ref that can be used to refer to a file in the repository, as staged
  - in the index.
@@ -64,12 +64,12 @@ fileFromRef (Ref r) f = let (Ref fr) = fileRef f in Ref (r ++ fr)
 {- Checks if a ref exists. -}
 exists :: Ref -> Repo -> IO Bool
 exists ref = runBool
-	[Param "show-ref", Param "--verify", Param "-q", Param $ show ref]
+	[Param "show-ref", Param "--verify", Param "-q", Param $ fromRef ref]
 
 {- The file used to record a ref. (Git also stores some refs in a
  - packed-refs file.) -}
 file :: Ref -> Repo -> FilePath
-file ref repo = localGitDir repo </> show ref
+file ref repo = localGitDir repo </> fromRef ref
 
 {- Checks if HEAD exists. It generally will, except for in a repository
  - that was just created. -}
@@ -84,17 +84,17 @@ sha branch repo = process <$> showref repo
   where
 	showref = pipeReadStrict [Param "show-ref",
 		Param "--hash", -- get the hash
-		Param $ show branch]
+		Param $ fromRef branch]
 	process [] = Nothing
 	process s = Just $ Ref $ firstLine s
 
 {- List of (shas, branches) matching a given ref or refs. -}
 matching :: [Ref] -> Repo -> IO [(Sha, Branch)]
-matching refs repo =  matching' (map show refs) repo
+matching refs repo =  matching' (map fromRef refs) repo
 
 {- Includes HEAD in the output, if asked for it. -}
 matchingWithHEAD :: [Ref] -> Repo -> IO [(Sha, Branch)]
-matchingWithHEAD refs repo = matching' ("--head" : map show refs) repo
+matchingWithHEAD refs repo = matching' ("--head" : map fromRef refs) repo
 
 {- List of (shas, branches) matching a given ref or refs. -}
 matching' :: [String] -> Repo -> IO [(Sha, Branch)]
@@ -114,7 +114,7 @@ matchingUniq refs repo = nubBy uniqref <$> matching refs repo
 {- Gets the sha of the tree a ref uses. -}
 tree :: Ref -> Repo -> IO (Maybe Sha)
 tree ref = extractSha <$$> pipeReadStrict
-	[ Param "rev-parse", Param (show ref ++ ":") ]
+	[ Param "rev-parse", Param (fromRef ref ++ ":") ]
 
 {- Checks if a String is a legal git ref name.
  -

Git/RefLog.hs

@@ -18,5 +18,5 @@ get b = mapMaybe extractSha . lines <$$> pipeReadStrict
 	[ Param "log"
 	, Param "-g"
 	, Param "--format=%H"
-	, Param (show b)
+	, Param (fromRef b)
 	]

Git/Repair.hs

@@ -168,7 +168,7 @@ resetLocalBranches :: MissingObjects -> GoodCommits -> Repo -> IO ([Branch], [Br
 resetLocalBranches missing goodcommits r =
 	go [] [] goodcommits =<< filter islocalbranch <$> getAllRefs r
   where
-	islocalbranch b = "refs/heads/" `isPrefixOf` show b
+	islocalbranch b = "refs/heads/" `isPrefixOf` fromRef b
 	go changed deleted gcs [] = return (changed, deleted, gcs)
 	go changed deleted gcs (b:bs) = do
 		(mc, gcs') <- findUncorruptedCommit missing gcs b r
@@ -185,12 +185,12 @@ resetLocalBranches missing goodcommits r =
 		nukeBranchRef b	r
 		void $ runBool
 			[ Param "branch"
-			, Param (show $ Ref.base b)
-			, Param (show c)
+			, Param (fromRef $ Ref.base b)
+			, Param (fromRef c)
 			] r
 
 isTrackingBranch :: Ref -> Bool
-isTrackingBranch b = "refs/remotes/" `isPrefixOf` show b
+isTrackingBranch b = "refs/remotes/" `isPrefixOf` fromRef b
 
 {- To deal with missing objects that cannot be recovered, removes
  - any branches (filtered by a predicate) that reference them
@@ -231,10 +231,10 @@ explodePackedRefsFile r = do
 		nukeFile f
   where
 	makeref (sha, ref) = do
-		let dest = localGitDir r </> show ref
+		let dest = localGitDir r </> fromRef ref
 		createDirectoryIfMissing True (parentDir dest)
 		unlessM (doesFileExist dest) $
-			writeFile dest (show sha)
+			writeFile dest (fromRef sha)
 
 packedRefsFile :: Repo -> FilePath
 packedRefsFile r = localGitDir r </> "packed-refs"
@@ -249,7 +249,7 @@ parsePacked l = case words l of
 {- git-branch -d cannot be used to remove a branch that is directly
  - pointing to a corrupt commit. -}
 nukeBranchRef :: Branch -> Repo -> IO ()
-nukeBranchRef b r = nukeFile $ localGitDir r </> show b
+nukeBranchRef b r = nukeFile $ localGitDir r </> fromRef b
 
 {- Finds the most recent commit to a branch that does not need any
  - of the missing objects. If the input branch is good as-is, returns it.
@@ -268,7 +268,7 @@ findUncorruptedCommit missing goodcommits branch r = do
 				[ Param "log"
 				, Param "-z"
 				, Param "--format=%H"
-				, Param (show branch)
+				, Param (fromRef branch)
 				] r
 			let branchshas = catMaybes $ map extractSha ls
 			reflogshas <- RefLog.get branch r
@@ -297,7 +297,7 @@ verifyCommit missing goodcommits commit r
 			[ Param "log"
 			, Param "-z"
 			, Param "--format=%H %T"
-			, Param (show commit)
+			, Param (fromRef commit)
 			] r
 		let committrees = map parse ls
 		if any isNothing committrees || null committrees
@@ -501,9 +501,9 @@ runRepair' removablebranch fsckresult forced referencerepo g = do
 				, "remote tracking branches that referred to missing objects."
 				]
 		(resetbranches, deletedbranches, _) <- resetLocalBranches stillmissing goodcommits g
-		displayList (map show resetbranches)
+		displayList (map fromRef resetbranches)
 			"Reset these local branches to old versions before the missing objects were committed:"
-		displayList (map show deletedbranches)
+		displayList (map fromRef deletedbranches)
 			"Deleted these local branches, which could not be recovered due to missing objects:"
 		deindexedfiles <- rewriteIndex g
 		displayList deindexedfiles
@@ -519,7 +519,7 @@ runRepair' removablebranch fsckresult forced referencerepo g = do
 						Just curr -> when (any (== curr) modifiedbranches) $ do
 							putStrLn $ unwords
 								[ "You currently have"
-								, show curr
+								, fromRef curr
 								, "checked out. You may have staged changes in the index that can be committed to recover the lost state of this branch!"
 								]
 				putStrLn "Successfully recovered repository!"

Git/Types.hs

@@ -47,10 +47,10 @@ type RemoteName = String
 
 {- A git ref. Can be a sha1, or a branch or tag name. -}
 newtype Ref = Ref String
-	deriving (Eq, Ord)
+	deriving (Eq, Ord, Read, Show)
 
-instance Show Ref where
-	show (Ref v) = v
+fromRef :: Ref -> String
+fromRef (Ref s) = s
 
 {- Aliases for Ref. -}
 type Branch = Ref

Git/UpdateIndex.hs

@@ -79,7 +79,7 @@ lsTree (Ref x) repo streamer = do
  - a given file with a given sha. -}
 updateIndexLine :: Sha -> BlobType -> TopFilePath -> String
 updateIndexLine sha filetype file =
-	show filetype ++ " blob " ++ show sha ++ "\t" ++ indexPath file
+	show filetype ++ " blob " ++ fromRef sha ++ "\t" ++ indexPath file
 
 stageFile :: Sha -> BlobType -> FilePath -> Repo -> IO Streamer
 stageFile sha filetype file repo = do
@@ -90,7 +90,7 @@ stageFile sha filetype file repo = do
 unstageFile :: FilePath -> Repo -> IO Streamer
 unstageFile file repo = do
 	p <- toTopFilePath file repo
-	return $ pureStreamer $ "0 " ++ show nullSha ++ "\t" ++ indexPath p
+	return $ pureStreamer $ "0 " ++ fromRef nullSha ++ "\t" ++ indexPath p
 
 {- A streamer that adds a symlink to the index. -}
 stageSymlink :: FilePath -> Sha -> Repo -> IO Streamer

Logs/FsckResults.hs

@@ -31,7 +31,7 @@ writeFsckResults u fsckresults = do
   	store s logfile = do 
 		createDirectoryIfMissing True (parentDir logfile)
 		liftIO $ viaTmp writeFile logfile $ serialize s
-	serialize = unlines . map show . S.toList
+	serialize = unlines . map fromRef . S.toList
 
 readFsckResults :: UUID -> Annex FsckResults
 readFsckResults u = do

Logs/View.hs

@@ -24,21 +24,12 @@ import Types.MetaData
 import qualified Git
 import qualified Git.Branch
 import qualified Git.Ref
+import Git.Types
 import Utility.Tmp
 
 import qualified Data.Set as S
 import Data.Char
 
-showLog :: View -> String
-showLog (View branch components) = show branch ++ " " ++ show components
-
-parseLog :: String -> Maybe View
-parseLog s = 
-	let (branch, components) = separate (== ' ') s
-	in View
-		<$> pure (Git.Ref branch)
-		<*> readish components
-
 setView :: View -> Annex ()
 setView v = do
 	old <- take 99 . filter (/= v) <$> recentViews
@@ -47,7 +38,7 @@ setView v = do
 writeViews :: [View] -> Annex ()
 writeViews l = do
 	f <- fromRepo gitAnnexViewLog
-	liftIO $ viaTmp writeFile f $ unlines $ map showLog l
+	liftIO $ viaTmp writeFile f $ unlines $ map show l
 
 removeView :: View -> Annex ()
 removeView v = writeViews =<< filter (/= v) <$> recentViews
@@ -55,7 +46,7 @@ removeView v = writeViews =<< filter (/= v) <$> recentViews
 recentViews :: Annex [View]
 recentViews = do
 	f <- fromRepo gitAnnexViewLog
-	liftIO $ mapMaybe parseLog . lines <$> catchDefaultIO [] (readFile f)
+	liftIO $ mapMaybe readish . lines <$> catchDefaultIO [] (readFile f)
 
 {- Gets the currently checked out view, if there is one. -}
 currentView :: Annex (Maybe View)
@@ -97,4 +88,4 @@ branchView view
 		| otherwise = map (\c -> if isAlphaNum c then c else '_') s
 
 prop_branchView_legal :: View -> Bool
-prop_branchView_legal = Git.Ref.legal False . show . branchView
+prop_branchView_legal = Git.Ref.legal False . fromRef . branchView

Remote/GCrypt.hs

@@ -177,7 +177,7 @@ gCryptSetup mu _ c = go $ M.lookup "gitrepo" c
 		void $ inRepo $ Git.Command.runBool
 			[ Param "push"
 			, Param remotename
-			, Param $ show Annex.Branch.fullname
+			, Param $ Git.fromRef Annex.Branch.fullname
 			]
 		g <- inRepo Git.Config.reRead
 		case Git.GCrypt.remoteRepoId g (Just remotename) of

Types/View.hs

@@ -20,7 +20,7 @@ data View = View
 	{ viewParentBranch :: Git.Branch
 	, viewComponents :: [ViewComponent]
 	}
-	deriving (Eq, Show)
+	deriving (Eq, Read, Show)
 
 instance Arbitrary View where
 	arbitrary = View <$> pure (Git.Ref "master") <*> arbitrary
@@ -29,7 +29,7 @@ data ViewComponent = ViewComponent
 	{ viewField :: MetaField
 	, viewFilter :: ViewFilter
 	}
-	deriving (Eq, Show, Read)
+	deriving (Eq, Read, Show)
 
 instance Arbitrary ViewComponent where
 	arbitrary = ViewComponent <$> arbitrary <*> arbitrary
@@ -41,7 +41,7 @@ type MkFileView = FilePath -> FileView
 data ViewFilter
 	= FilterValues (S.Set MetaValue)
 	| FilterGlob String
-	deriving (Eq, Show, Read)
+	deriving (Eq, Read, Show)
 
 instance Arbitrary ViewFilter where
 	arbitrary = do

Upgrade/V2.hs

@@ -106,7 +106,10 @@ push = do
 			showAction "pushing new git-annex branch to origin"
 			showOutput
 			inRepo $ Git.Command.run
-				[Param "push", Param "origin", Param $ show Annex.Branch.name]
+				[ Param "push"
+				, Param "origin"
+				, Param $ Git.fromRef Annex.Branch.name
+				]
 		_ -> do
 			-- no origin exists, so just let the user
 			-- know about the new branch