diff --git a/src/Options/Applicative/Complicated.hs b/src/Options/Applicative/Complicated.hs
index f6dc0b14fa..ecf94aa97a 100644
--- a/src/Options/Applicative/Complicated.hs
+++ b/src/Options/Applicative/Complicated.hs
@@ -44,7 +44,7 @@ complicatedOptions
   -> ExceptT b (Writer (Mod CommandFields (b,a))) ()
   -- ^ commands (use 'addCommand')
   -> IO (a,b)
-complicatedOptions numericVersion versionString numericHpackVersion h pd footerStr commonParser mOnFailure commandParser =
+complicatedOptions numericVersion stringVersion numericHpackVersion h pd footerStr commonParser mOnFailure commandParser =
   do args <- getArgs
      (a,(b,c)) <- case execParserPure (prefs noBacktrack) parser args of
        Failure _ | null args -> withArgs ["--help"] (execParser parser)
@@ -55,8 +55,8 @@ complicatedOptions numericVersion versionString numericHpackVersion h pd footerS
   where parser = info (helpOption <*> versionOptions <*> complicatedParser "COMMAND|FILE" commonParser commandParser) desc
         desc = fullDesc <> header h <> progDesc pd <> footer footerStr
         versionOptions =
-          case versionString of
-            Nothing -> versionOption (displayC numericVersion)
+          case stringVersion of
+            Nothing -> versionOption (versionString numericVersion)
             Just s -> versionOption s <*> numericVersionOption <*> numericHpackVersionOption
         versionOption s =
           infoOption
@@ -65,7 +65,7 @@ complicatedOptions numericVersion versionString numericHpackVersion h pd footerS
              help "Show version")
         numericVersionOption =
           infoOption
-            (displayC numericVersion)
+            (versionString numericVersion)
             (long "numeric-version" <>
              help "Show only version number")
         numericHpackVersionOption =
diff --git a/src/Stack/Build.hs b/src/Stack/Build.hs
index 950b3ee8c3..40a8f88acb 100644
--- a/src/Stack/Build.hs
+++ b/src/Stack/Build.hs
@@ -155,7 +155,7 @@ checkCabalVersion = do
     when (allowNewer && cabalVer < $(mkVersion "1.22")) $ throwM $
         CabalVersionException $
             "Error: --allow-newer requires at least Cabal version 1.22, but version " ++
-            displayC cabalVer ++
+            versionString cabalVer ++
             " was found."
 
 newtype CabalVersionException = CabalVersionException { unCabalVersionException :: String }
@@ -176,7 +176,7 @@ warnIfExecutablesWithSameNameCouldBeOverwritten locals plan = do
             exesText pkgs =
                 T.intercalate
                     ", "
-                    ["'" <> displayC p <> ":" <> exe <> "'" | p <- pkgs]
+                    ["'" <> T.pack (packageNameString p) <> ":" <> exe <> "'" | p <- pkgs]
         (logWarn . display . T.unlines . concat)
             [ [ "Building " <> exe_s <> " " <> exesText toBuild <> "." ]
             , [ "Only one of them will be available via 'stack exec' or locally installed."
@@ -389,7 +389,7 @@ rawBuildInfo = do
         ]
   where
     localToPair lp =
-        (displayC $ packageName p, value)
+        (T.pack $ packageNameString $ packageName p, value)
       where
         p = lpPackage lp
         value = object
diff --git a/src/Stack/Build/Cache.hs b/src/Stack/Build/Cache.hs
index bb43bfda27..e0773d755f 100644
--- a/src/Stack/Build/Cache.hs
+++ b/src/Stack/Build/Cache.hs
@@ -86,7 +86,7 @@ markExeInstalled :: (MonadReader env m, HasEnvConfig env, MonadIO m, MonadThrow
 markExeInstalled loc ident = do
     dir <- exeInstalledDir loc
     ensureDir dir
-    ident' <- parseRelFile $ displayC ident
+    ident' <- parseRelFile $ packageIdentifierString ident
     let fp = toFilePath $ dir </> ident'
     -- Remove old install records for this package.
     -- TODO: This is a bit in-efficient. Put all this metadata into one file?
@@ -103,7 +103,7 @@ markExeNotInstalled :: (MonadReader env m, HasEnvConfig env, MonadIO m, MonadThr
                     => InstallLocation -> PackageIdentifier -> m ()
 markExeNotInstalled loc ident = do
     dir <- exeInstalledDir loc
-    ident' <- parseRelFile $ displayC ident
+    ident' <- parseRelFile $ packageIdentifierString ident
     liftIO $ ignoringAbsence (removeFile $ dir </> ident')
 
 buildCacheFile :: (HasEnvConfig env, MonadReader env m, MonadThrow m)
@@ -185,7 +185,7 @@ flagCacheFile installed = do
     rel <- parseRelFile $
         case installed of
             Library _ gid _ -> ghcPkgIdString gid
-            Executable ident -> displayC ident
+            Executable ident -> packageIdentifierString ident
     dir <- flagCacheLocal
     return $ dir </> rel
 
@@ -257,7 +257,7 @@ precompiledCacheFile loc copts installedPackageIDs = do
   ec <- view envConfigL
 
   compiler <- view actualCompilerVersionL >>= parseRelDir . compilerVersionString
-  cabal <- view cabalVersionL >>= parseRelDir . displayC
+  cabal <- view cabalVersionL >>= parseRelDir . versionString
 
   -- The goal here is to come up with a string representing the
   -- package location which is unique. Luckily @TreeKey@s are exactly
diff --git a/src/Stack/Build/ConstructPlan.hs b/src/Stack/Build/ConstructPlan.hs
index 69725386cb..5efddb2d0a 100644
--- a/src/Stack/Build/ConstructPlan.hs
+++ b/src/Stack/Build/ConstructPlan.hs
@@ -315,7 +315,7 @@ mkUnregisterLocal tasks dirtyReason localDumpPkgs sourceMap initialBuildSteps =
           = Just "Switching to snapshot installed package"
       -- Check if a dependency is going to be unregistered
       | (dep, _):_ <- mapMaybe (`Map.lookup` toUnregister) deps
-          = Just $ "Dependency being unregistered: " <> displayC dep
+          = Just $ "Dependency being unregistered: " <> T.pack (packageIdentifierString dep)
       -- None of the above, keep it!
       | otherwise = Nothing
       where
@@ -539,7 +539,7 @@ installPackageGivenDeps isAllInOne ps package minstalled (missing, present, minL
             shouldInstall <- checkDirtiness ps installed package present (wanted ctx)
             return $ if shouldInstall then Nothing else Just installed
         (Just _, False) -> do
-            let t = T.intercalate ", " $ map (displayC . pkgName) (Set.toList missing)
+            let t = T.intercalate ", " $ map (T.pack . packageNameString . pkgName) (Set.toList missing)
             tell mempty { wDirty = Map.singleton name $ "missing dependencies: " <> addEllipsis t }
             return Nothing
         (Nothing, _) -> return Nothing
@@ -643,9 +643,9 @@ addPackageDeps treatAsDep package = do
                                     [ "WARNING: Ignoring out of range dependency"
                                     , reason
                                     , ": "
-                                    , displayC $ PackageIdentifier depname (adrVersion adr)
+                                    , T.pack $ packageIdentifierString $ PackageIdentifier depname (adrVersion adr)
                                     , ". "
-                                    , displayC $ packageName package
+                                    , T.pack $ packageNameString $ packageName package
                                     , " requires: "
                                     , versionRangeText range
                                     ]
@@ -865,7 +865,7 @@ toolWarningText (ToolWarning (ExeName toolName) pkgName) =
     "No packages found in snapshot which provide a " <>
     T.pack (show toolName) <>
     " executable, which is a build-tool dependency of " <>
-    displayC pkgName
+    T.pack (packageNameString pkgName)
 
 -- | Strip out anything from the @Plan@ intended for the local database
 stripLocals :: Plan -> Plan
@@ -1005,7 +1005,7 @@ pprintExceptions exceptions stackYaml stackRoot parentMap wanted =
 
     pprintException (DependencyCycleDetected pNames) = Just $
         flow "Dependency cycle detected in packages:" <> line <>
-        indent 4 (encloseSep "[" "]" "," (map (style Error . displayC) pNames))
+        indent 4 (encloseSep "[" "]" "," (map (style Error . fromString . packageNameString) pNames))
     pprintException (DependencyPlanFailures pkg pDeps) =
         case mapMaybe pprintDep (Map.toList pDeps) of
             [] -> Nothing
@@ -1019,18 +1019,18 @@ pprintExceptions exceptions stackYaml stackRoot parentMap wanted =
                     Just (target:path) -> line <> flow "needed due to" <+> encloseSep "" "" " -> " pathElems
                       where
                         pathElems =
-                            [style Target . displayC $ target] ++
-                            map displayC path ++
+                            [style Target . fromString . packageIdentifierString $ target] ++
+                            map (fromString . packageIdentifierString) path ++
                             [pkgIdent]
               where
-                pkgName = style Current . displayC $ packageName pkg
-                pkgIdent = style Current . displayC $ packageIdentifier pkg
+                pkgName = style Current . fromString . packageNameString $ packageName pkg
+                pkgIdent = style Current . fromString . packageIdentifierString $ packageIdentifier pkg
     -- Skip these when they are redundant with 'NotInBuildPlan' info.
     pprintException (UnknownPackage name)
         | name `Set.member` allNotInBuildPlan = Nothing
         | name `Set.member` wiredInPackages =
-            Just $ flow "Can't build a package with same name as a wired-in-package:" <+> (style Current . displayC $ name)
-        | otherwise = Just $ flow "Unknown package:" <+> (style Current . displayC $ name)
+            Just $ flow "Can't build a package with same name as a wired-in-package:" <+> (style Current . fromString . packageNameString $ name)
+        | otherwise = Just $ flow "Unknown package:" <+> (style Current . fromString . packageNameString $ name)
 
     pprintFlags flags
         | Map.null flags = ""
@@ -1040,7 +1040,7 @@ pprintExceptions exceptions stackYaml stackRoot parentMap wanted =
 
     pprintDep (name, (range, mlatestApplicable, badDep)) = case badDep of
         NotInBuildPlan -> Just $
-            style Error (displayC name) <+>
+            style Error (fromString $ packageNameString name) <+>
             align ((if range == Cabal.anyVersion
                       then flow "needed"
                       else flow "must match" <+> goodRange) <> "," <> softline <>
@@ -1048,7 +1048,7 @@ pprintExceptions exceptions stackYaml stackRoot parentMap wanted =
                    latestApplicable Nothing)
         -- TODO: For local packages, suggest editing constraints
         DependencyMismatch version -> Just $
-            (style Error . displayC) (PackageIdentifier name version) <+>
+            (style Error . fromString . packageIdentifierString) (PackageIdentifier name version) <+>
             align (flow "from stack configuration does not match" <+> goodRange <+>
                    latestApplicable (Just version))
         -- I think the main useful info is these explain why missing
@@ -1056,11 +1056,11 @@ pprintExceptions exceptions stackYaml stackRoot parentMap wanted =
         -- path from a target to the package.
         Couldn'tResolveItsDependencies _version -> Nothing
         HasNoLibrary -> Just $
-            style Error (displayC name) <+>
+            style Error (fromString $ packageNameString name) <+>
             align (flow "is a library dependency, but the package provides no library")
         BDDependencyCycleDetected names -> Just $
-            style Error (displayC name) <+>
-            align (flow $ "dependency cycle detected: " ++ intercalate ", " (map displayC names))
+            style Error (fromString $ packageNameString name) <+>
+            align (flow $ "dependency cycle detected: " ++ intercalate ", " (map packageNameString names))
       where
         goodRange = style Good (fromString (Cabal.display range))
         latestApplicable mversion =
@@ -1073,7 +1073,7 @@ pprintExceptions exceptions stackYaml stackRoot parentMap wanted =
                     | Just laVer == mversion -> softline <>
                         flow "(latest matching version is specified)"
                     | otherwise -> softline <>
-                        flow "(latest matching version is" <+> style Good (displayC laVer) <> ")"
+                        flow "(latest matching version is" <+> style Good (fromString $ versionString laVer) <> ")"
 
 -- | Get the shortest reason for the package to be in the build plan. In
 -- other words, trace the parent dependencies back to a 'wanted'
@@ -1126,14 +1126,14 @@ data DepsPath = DepsPath
 startDepsPath :: PackageIdentifier -> DepsPath
 startDepsPath ident = DepsPath
     { dpLength = 1
-    , dpNameLength = T.length (displayC (pkgName ident))
+    , dpNameLength = length (packageNameString (pkgName ident))
     , dpPath = [ident]
     }
 
 extendDepsPath :: PackageIdentifier -> DepsPath -> DepsPath
 extendDepsPath ident dp = DepsPath
     { dpLength = dpLength dp + 1
-    , dpNameLength = dpNameLength dp + T.length (displayC (pkgName ident))
+    , dpNameLength = dpNameLength dp + length (packageNameString (pkgName ident))
     , dpPath = [ident]
     }
 
diff --git a/src/Stack/Build/Execute.hs b/src/Stack/Build/Execute.hs
index f7416c5593..df1419854d 100644
--- a/src/Stack/Build/Execute.hs
+++ b/src/Stack/Build/Execute.hs
@@ -124,7 +124,7 @@ printPlan plan = do
         xs -> do
             logInfo "Would unregister locally:"
             forM_ xs $ \(ident, reason) -> logInfo $
-                displayC ident <>
+                fromString (packageIdentifierString ident) <>
                 if T.null reason
                   then ""
                   else " (" <> RIO.display reason <> ")"
@@ -168,7 +168,7 @@ printPlan plan = do
 -- | For a dry run
 displayTask :: Task -> Utf8Builder
 displayTask task =
-    displayC (taskProvides task) <>
+    fromString (packageIdentifierString (taskProvides task)) <>
     ": database=" <>
     (case taskLocation task of
         Snap -> "snapshot"
@@ -180,7 +180,7 @@ displayTask task =
     (if Set.null missing
         then ""
         else ", after: " <>
-             mconcat (intersperse "," (displayC <$> Set.toList missing)))
+             mconcat (intersperse "," (fromString . packageIdentifierString <$> Set.toList missing)))
   where
     missing = tcoMissing $ taskConfigOpts task
 
@@ -250,7 +250,7 @@ getSetupExe setupHs setupShimHs tmpdir = do
     wc <- view $ actualCompilerVersionL.whichCompilerL
     platformDir <- platformGhcRelDir
     config <- view configL
-    cabalVersionString <- view $ cabalVersionL.to displayC
+    cabalVersionString <- view $ cabalVersionL.to versionString
     actualCompilerVersionString <- view $ actualCompilerVersionL.to compilerVersionString
     platform <- view platformL
     let baseNameS = concat
@@ -597,7 +597,7 @@ executePlan' installedMap0 targets plan ee@ExecuteEnv {..} = do
             localDB <- packageDatabaseLocal
             forM_ ids $ \(id', (ident, reason)) -> do
                 logInfo $
-                    displayC ident <>
+                    fromString (packageIdentifierString ident) <>
                     ": unregistering" <>
                     if T.null reason
                         then ""
@@ -631,10 +631,10 @@ executePlan' installedMap0 targets plan ee@ExecuteEnv {..} = do
                     run $ logStickyDone ("Completed " <> RIO.display total <> " action(s).")
                 | otherwise = do
                     inProgress <- readTVarIO actionsVar
-                    let packageNames = map (\(ActionId pkgID _) -> displayC pkgID) (toList inProgress)
+                    let packageNames = map (\(ActionId pkgID _) -> pkgName pkgID) (toList inProgress)
                         nowBuilding :: [PackageName] -> Utf8Builder
                         nowBuilding []    = ""
-                        nowBuilding names = mconcat $ ": " : intersperse ", " (map displayC names)
+                        nowBuilding names = mconcat $ ": " : intersperse ", " (map (fromString . packageNameString) names)
                     when terminal $ run $
                         logSticky $
                             "Progress " <> RIO.display prev <> "/" <> RIO.display total <>
@@ -872,7 +872,7 @@ ensureConfig newConfigCache pkgDir ExecuteEnv {..} announce cabal cabalfp task =
 
 announceTask :: HasLogFunc env => Task -> Text -> RIO env ()
 announceTask task x = logInfo $
-    displayC (taskProvides task) <>
+    fromString (packageIdentifierString (taskProvides task)) <>
     ": " <>
     RIO.display x
 
@@ -944,7 +944,7 @@ withSingleContext ActionContext {..} ExecuteEnv {..} task@Task {..} mdeps msuffi
         case taskType of
             TTFilePath lp _ -> inner (lpPackage lp) (lpCabalFile lp) (parent $ lpCabalFile lp)
             TTRemote package _ pkgloc -> do
-                suffix <- parseRelDir $ displayC $ packageIdent package
+                suffix <- parseRelDir $ packageIdentifierString $ packageIdent package
                 let dir = eeTempDir </> suffix
                 unpackPackageLocation dir pkgloc
 
@@ -963,14 +963,15 @@ withSingleContext ActionContext {..} ExecuteEnv {..} task@Task {..} mdeps msuffi
                   renameDir oldDist newDist
 
                 let name = pkgName taskProvides
-                cabalfpRel <- parseRelFile $ displayC name ++ ".cabal"
+                cabalfpRel <- parseRelFile $ packageNameString name ++ ".cabal"
                 let cabalfp = dir </> cabalfpRel
                 inner package cabalfp dir
 
     withOutputType pkgDir package inner
         -- If the user requested interleaved output, dump to the console with a
         -- prefix.
-        | boptsInterleavedOutput eeBuildOpts = inner $ OTConsole $ displayC (packageName package) <> "> "
+        | boptsInterleavedOutput eeBuildOpts =
+            inner $ OTConsole $ fromString (packageNameString (packageName package)) <> "> "
 
         -- Not in interleaved mode. When building a single wanted package, dump
         -- to the console with no prefix.
@@ -1025,7 +1026,7 @@ withSingleContext ActionContext {..} ExecuteEnv {..} task@Task {..} mdeps msuffi
                     -- https://github.com/commercialhaskell/stack/issues/1356
                     | packageName package == $(mkPackageName "Cabal") = []
                     | otherwise =
-                        ["-package=" ++ displayC
+                        ["-package=" ++ packageIdentifierString
                                             (PackageIdentifier cabalPackageName
                                                               eeCabalPkgVer)]
                 packageDBArgs =
@@ -1044,7 +1045,7 @@ withSingleContext ActionContext {..} ExecuteEnv {..} task@Task {..} mdeps msuffi
                         (TTFilePath lp Local, C.Custom) | lpWanted lp -> do
                             prettyWarnL
                                 [ flow "Package"
-                                , displayC $ packageName package
+                                , fromString $ packageNameString $ packageName package
                                 , flow "uses a custom Cabal build, but does not use a custom-setup stanza"
                                 ]
                         _ -> return ()
@@ -1060,7 +1061,7 @@ withSingleContext ActionContext {..} ExecuteEnv {..} task@Task {..} mdeps msuffi
                         (Just customSetupDeps, _) -> do
                             unless (Map.member $(mkPackageName "Cabal") customSetupDeps) $
                                 prettyWarnL
-                                    [ displayC $ packageName package
+                                    [ fromString $ packageNameString $ packageName package
                                     , "has a setup-depends field, but it does not mention a Cabal dependency. This is likely to cause build errors."
                                     ]
                             allDeps <-
@@ -1076,11 +1077,11 @@ withSingleContext ActionContext {..} ExecuteEnv {..} task@Task {..} mdeps msuffi
                                 case filter (matches . fst) (Map.toList allDeps) of
                                     x:xs -> do
                                         unless (null xs)
-                                            (logWarn ("Found multiple installed packages for custom-setup dep: " <> displayC name))
+                                            (logWarn ("Found multiple installed packages for custom-setup dep: " <> fromString (packageNameString name)))
                                         return ("-package-id=" ++ ghcPkgIdString (snd x), Just (fst x))
                                     [] -> do
-                                        logWarn ("Could not find custom-setup dep: " <> displayC name)
-                                        return ("-package=" ++ displayC name, Nothing)
+                                        logWarn ("Could not find custom-setup dep: " <> fromString (packageNameString name))
+                                        return ("-package=" ++ packageNameString name, Nothing)
                             let depsArgs = map fst matchedDeps
                             -- Generate setup_macros.h and provide it to ghc
                             let macroDeps = mapMaybe snd matchedDeps
@@ -1342,8 +1343,8 @@ singleBuild ac@ActionContext {..} ee@ExecuteEnv {..} task@Task {..} installedMap
             TTFilePath lp _ -> packageInternalLibraries $ lpPackage lp
             TTRemote p _ _ -> packageInternalLibraries p
           PackageIdentifier name version = taskProvides
-          mainLibName = displayC name
-          mainLibVersion = displayC version
+          mainLibName = packageNameString name
+          mainLibVersion = versionString version
           pkgName = mainLibName ++ "-" ++ mainLibVersion
           -- z-package-z-internal for internal lib internal of package package
           toCabalInternalLibName n = concat ["z-", mainLibName, "-z-", n, "-", mainLibVersion]
@@ -1401,7 +1402,7 @@ singleBuild ac@ActionContext {..} ee@ExecuteEnv {..} task@Task {..} installedMap
             executableBuildStatuses <- getExecutableBuildStatuses package pkgDir
             when (not (cabalIsSatisfied executableBuildStatuses) && taskIsTarget task)
                  (logInfo
-                      ("Building all executables for `" <> displayC (packageName package) <>
+                      ("Building all executables for `" <> fromString (packageNameString (packageName package)) <>
                        "' once. After a successful build of all of them, only specified executables will be rebuilt."))
 
             _neededConfig <- ensureConfig cache pkgDir ee (announce ("configure" <> annSuffix executableBuildStatuses)) cabal cabalfp task
@@ -1590,7 +1591,7 @@ singleBuild ac@ActionContext {..} ee@ExecuteEnv {..} task@Task {..} installedMap
                 sublibsPkgIds <- fmap catMaybes $
                   forM (Set.toList $ packageInternalLibraries package) $ \sublib -> do
                     -- z-haddock-library-z-attoparsec for internal lib attoparsec of haddock-library
-                    let sublibName = T.concat ["z-", displayC $ packageName package, "-z-", sublib]
+                    let sublibName = T.concat ["z-", T.pack $ packageNameString $ packageName package, "-z-", sublib]
                     case parsePackageName $ T.unpack sublibName of
                       Nothing -> return Nothing -- invalid lib, ignored
                       Just subLibName -> loadInstalledPkg wc [installedPkgDb] installedDumpPkgsTVar subLibName
@@ -1840,7 +1841,7 @@ singleTest topts testsToRun ac ee task installedMap = do
                         logError $ displayShow $ TestSuiteExeMissing
                             (packageBuildType package == C.Simple)
                             exeName
-                            (displayC (packageName package))
+                            (packageNameString (packageName package))
                             (T.unpack testName)
                         return $ Map.singleton testName Nothing
 
@@ -2012,7 +2013,7 @@ primaryComponentOptions executableBuildStatuses lp =
          NoLibraries -> []
          HasLibraries names ->
              map T.unpack
-           $ T.append "lib:" (displayC (packageName package))
+           $ T.append "lib:" (T.pack (packageNameString (packageName package)))
            : map (T.append "flib:") (Set.toList names)) ++
       map (T.unpack . T.append "lib:") (Set.toList $ packageInternalLibraries package) ++
       map (T.unpack . T.append "exe:") (Set.toList $ exesToBuild executableBuildStatuses lp)
diff --git a/src/Stack/Build/Haddock.hs b/src/Stack/Build/Haddock.hs
index c04f84375f..fc7e99e644 100644
--- a/src/Stack/Build/Haddock.hs
+++ b/src/Stack/Build/Haddock.hs
@@ -62,7 +62,7 @@ openHaddocksInBrowser bco pkgLocations buildTargets = do
     docFile <-
         case (cliTargets, map (`Map.lookup` pkgLocations) (Set.toList buildTargets)) of
             ([_], [Just (pkgId, iloc)]) -> do
-                pkgRelDir <- (parseRelDir . displayC) pkgId
+                pkgRelDir <- (parseRelDir . packageIdentifierString) pkgId
                 let docLocation =
                         case iloc of
                             Snap -> snapDocDir bco
@@ -234,8 +234,8 @@ generateHaddockIndex descr wc bco dumpPackages docRelFP destDir = do
                 let (PackageIdentifier name _) = dpPackageIdent
                     destInterfaceRelFP =
                         docRelFP FP.</>
-                        displayC dpPackageIdent FP.</>
-                        (displayC name FP.<.> "haddock")
+                        packageIdentifierString dpPackageIdent FP.</>
+                        (packageNameString name FP.<.> "haddock")
                 destInterfaceAbsFile <- parseCollapsedAbsFile (toFilePath destDir FP.</> destInterfaceRelFP)
                 esrcInterfaceModTime <- tryGetModificationTime srcInterfaceAbsFile
                 return $
@@ -245,7 +245,7 @@ generateHaddockIndex descr wc bco dumpPackages docRelFP destDir = do
                             Just
                                 ( [ "-i"
                                   , concat
-                                        [ docRelFP FP.</> displayC dpPackageIdent
+                                        [ docRelFP FP.</> packageIdentifierString dpPackageIdent
                                         , ","
                                         , destInterfaceRelFP ]]
                                 , srcInterfaceModTime
diff --git a/src/Stack/Build/Installed.hs b/src/Stack/Build/Installed.hs
index c17b826961..9aab51f86d 100644
--- a/src/Stack/Build/Installed.hs
+++ b/src/Stack/Build/Installed.hs
@@ -171,16 +171,16 @@ processLoadResult _ True (WrongVersion actual wanted, lh)
     | fst (lhPair lh) `Set.member` ghcjsBootPackages = do
         logWarn $
             "Ignoring that the GHCJS boot package \"" <>
-            displayC (fst (lhPair lh)) <>
+            fromString (packageNameString (fst (lhPair lh))) <>
             "\" has a different version, " <>
-            displayC actual <>
+            fromString (versionString actual) <>
             ", than the resolver's wanted version, " <>
-            displayC wanted
+            fromString (versionString wanted)
         return (Just lh)
 processLoadResult mdb _ (reason, lh) = do
     logDebug $
         "Ignoring package " <>
-        displayC (fst (lhPair lh)) <>
+        fromString (packageNameString (fst (lhPair lh))) <>
         maybe mempty (\db -> ", from " <> displayShow db <> ",") mdb <>
         " due to" <>
         case reason of
@@ -192,9 +192,9 @@ processLoadResult mdb _ (reason, lh) = do
             WrongLocation mloc loc -> " wrong location: " <> displayShow (mloc, loc)
             WrongVersion actual wanted ->
                 " wanting version " <>
-                displayC wanted <>
+                fromString (versionString wanted) <>
                 " instead of " <>
-                displayC actual
+                fromString (versionString actual)
     return Nothing
 
 data Allowed
diff --git a/src/Stack/Build/Target.hs b/src/Stack/Build/Target.hs
index 8b009f4f83..b26fceefb0 100644
--- a/src/Stack/Build/Target.hs
+++ b/src/Stack/Build/Target.hs
@@ -103,7 +103,7 @@ getRawInput boptscli locals =
         textTargets =
             -- Handle the no targets case, which means we pass in the names of all project packages
             if null textTargets'
-                then map displayC (Map.keys locals)
+                then map (T.pack . packageNameString) (Map.keys locals)
                 else textTargets'
      in (textTargets', map RawInput textTargets)
 
@@ -254,7 +254,7 @@ resolveRawTarget globals snap deps locals (ri, rt) =
                     ]
     go (RTPackageComponent name ucomp) = return $
         case Map.lookup name locals of
-            Nothing -> Left $ T.pack $ "Unknown local package: " ++ displayC name
+            Nothing -> Left $ T.pack $ "Unknown local package: " ++ packageNameString name
             Just lpv ->
                 case ucomp of
                     ResolvedComponent comp
@@ -269,7 +269,7 @@ resolveRawTarget globals snap deps locals (ri, rt) =
                             [ "Component "
                             , show comp
                             , " does not exist in package "
-                            , displayC name
+                            , packageNameString name
                             ]
                     UnresolvedComponent comp ->
                         case filter (isCompNamed comp) $ Set.toList $ lpvComponents lpv of
@@ -277,7 +277,7 @@ resolveRawTarget globals snap deps locals (ri, rt) =
                                 [ "Component "
                                 , comp
                                 , " does not exist in package "
-                                , displayC name
+                                , T.pack $ packageNameString name
                                 ]
                             [x] -> Right ResolveResult
                               { rrName = name
@@ -290,7 +290,7 @@ resolveRawTarget globals snap deps locals (ri, rt) =
                                 [ "Ambiguous component name "
                                 , comp
                                 , " for package "
-                                , displayC name
+                                , T.pack $ packageNameString name
                                 , ": "
                                 , T.pack $ show matches
                                 ]
@@ -343,7 +343,7 @@ resolveRawTarget globals snap deps locals (ri, rt) =
 
     go (RTPackageIdentifier ident@(PackageIdentifier name version))
       | Map.member name locals = return $ Left $ T.concat
-            [ tshow (displayC name :: String)
+            [ tshow (packageNameString name)
             , " target has a specific version number, but it is a local package."
             , "\nTo avoid confusion, we will not install the specified version or build the local one."
             , "\nTo build the local package, specify the target without an explicit version."
@@ -369,7 +369,7 @@ resolveRawTarget globals snap deps locals (ri, rt) =
             -- index, so refuse to do the override
             Just loc' -> Left $ T.concat
               [ "Package with identifier was targeted on the command line: "
-              , displayC ident
+              , T.pack $ packageIdentifierString ident
               , ", but it was specified from a non-index location: "
               , T.pack $ show loc'
               , ".\nRecommendation: add the correctly desired version to extra-deps."
@@ -432,7 +432,7 @@ combineResolveResults results = do
                   | all isJust mcomps -> Right $ Map.singleton name $ TargetComps $ Set.fromList $ catMaybes mcomps
                   | otherwise -> Left $ T.concat
                       [ "The package "
-                      , displayC name
+                      , T.pack $ packageNameString name
                       , " was specified in multiple, incompatible ways: "
                       , T.unwords $ map (unRawInput . rrRaw) rrs
                       ]
diff --git a/src/Stack/BuildPlan.hs b/src/Stack/BuildPlan.hs
index 7da91fbac0..b74888c9e6 100644
--- a/src/Stack/BuildPlan.hs
+++ b/src/Stack/BuildPlan.hs
@@ -86,20 +86,20 @@ instance Show BuildPlanException where
                     [] -> []
                     noKnown ->
                         [ "There are no known versions of the following packages:"
-                        , intercalate ", " $ map displayC noKnown
+                        , intercalate ", " $ map packageNameString noKnown
                         ]
                 ]
           where
-            go (dep, (_, users)) | Set.null users = displayC dep
+            go (dep, (_, users)) | Set.null users = packageNameString dep
             go (dep, (_, users)) = concat
-                [ displayC dep
+                [ packageNameString dep
                 , " (used by "
-                , intercalate ", " $ map displayC $ Set.toList users
+                , intercalate ", " $ map packageNameString $ Set.toList users
                 , ")"
                 ]
 
             goRecommend (name, (Just version, _)) =
-                Just $ "- " ++ displayC (PackageIdentifier name version)
+                Just $ "- " ++ packageIdentifierString (PackageIdentifier name version)
             goRecommend (_, (Nothing, _)) = Nothing
 
             getNoKnown (name, (Nothing, _)) = Just name
@@ -118,17 +118,17 @@ instance Show BuildPlanException where
                 , ["Note: further dependencies may need to be added"]
                 ]
           where
-            go (dep, users) | Set.null users = displayC dep ++ " (internal stack error: this should never be null)"
+            go (dep, users) | Set.null users = packageNameString dep ++ " (internal stack error: this should never be null)"
             go (dep, users) = concat
-                [ displayC dep
+                [ packageNameString dep
                 , " (used by "
                 , intercalate ", "
-                    $ map (displayC . pkgName)
+                    $ map (packageNameString . pkgName)
                     $ Set.toList users
                 , ")"
                 ]
 
-            extraDeps = map (\ident -> "- " ++ displayC ident)
+            extraDeps = map (\ident -> "- " ++ packageIdentifierString ident)
                       $ Set.toList
                       $ Set.unions
                       $ Map.elems shadowed
@@ -427,7 +427,7 @@ showPackageFlags pkg fl =
     if not $ Map.null fl then
         T.concat
             [ "    - "
-            , T.pack $ displayC pkg
+            , T.pack $ packageNameString pkg
             , ": "
             , T.pack $ intercalate ", "
                      $ map formatFlags (Map.toList fl)
@@ -438,7 +438,7 @@ showPackageFlags pkg fl =
         formatFlags (f, v) = show f ++ " = " ++ show v
 
 showMapPackages :: Map PackageName a -> Text
-showMapPackages mp = showItems $ map displayC $ Map.keys mp
+showMapPackages mp = showItems $ map packageNameString $ Map.keys mp
 
 showCompilerErrors
     :: Map PackageName (Map FlagName Bool)
@@ -467,12 +467,12 @@ showDepErrors flags errs =
             ]
 
         showDepVersion depName mversion = T.concat
-            [ T.pack $ displayC depName
+            [ T.pack $ packageNameString depName
             , case mversion of
                 Nothing -> " not found"
                 Just version -> T.concat
                     [ " version "
-                    , T.pack $ displayC version
+                    , T.pack $ versionString version
                     , " found"
                     ]
             , "\n"
@@ -480,7 +480,7 @@ showDepErrors flags errs =
 
         showRequirement (user, range) = T.concat
             [ "    - "
-            , T.pack $ displayC user
+            , T.pack $ packageNameString user
             , " requires "
             , T.pack $ display range
             , "\n"
diff --git a/src/Stack/Config/Nix.hs b/src/Stack/Config/Nix.hs
index 517cbc8d46..e58e88426b 100644
--- a/src/Stack/Config/Nix.hs
+++ b/src/Stack/Config/Nix.hs
@@ -55,7 +55,7 @@ nixCompiler :: WantedCompiler -> Either StringException T.Text
 nixCompiler compilerVersion =
   case compilerVersion of
     WCGhc version ->
-      case T.split (== '.') (displayC version) of
+      case T.split (== '.') (fromString $ versionString version) of
         x : y : minor ->
           Right $
           case minor of
@@ -70,7 +70,7 @@ nixCompiler compilerVersion =
               \(lib.attrNames haskell.compiler); in \
               \if compilers == [] \
               \then abort \"No compiler found for GHC "
-              <> displayC version <> "\"\
+              <> T.pack (versionString version) <> "\"\
               \else haskell.compiler.${builtins.head compilers})"
             _ -> "haskell.compiler.ghc" <> T.concat (x : y : minor)
         _ -> Left $ stringException "GHC major version not specified"
diff --git a/src/Stack/Constants/Config.hs b/src/Stack/Constants/Config.hs
index 299cb5ca75..c1ca27fcab 100644
--- a/src/Stack/Constants/Config.hs
+++ b/src/Stack/Constants/Config.hs
@@ -126,7 +126,7 @@ distRelativeDir = do
     envDir <-
         parseRelDir $
         (if wc == Ghcjs then (++ "_ghcjs") else id) $
-        displayC $
+        packageIdentifierString $
         PackageIdentifier cabalPackageName cabalPkgVer
     platformAndCabal <- useShaPathOnWindows (platform </> envDir)
     workDir <- view workDirL
diff --git a/src/Stack/Coverage.hs b/src/Stack/Coverage.hs
index 54b087066a..76c0ab0a6d 100644
--- a/src/Stack/Coverage.hs
+++ b/src/Stack/Coverage.hs
@@ -81,7 +81,7 @@ updateTixFile pkgName' tixSrc testName = do
 hpcPkgPath :: HasEnvConfig env => PackageName -> RIO env (Path Abs Dir)
 hpcPkgPath pkgName' = do
     outputDir <- hpcReportDir
-    pkgNameRel <- parseRelDir (displayC pkgName')
+    pkgNameRel <- parseRelDir (packageNameString pkgName')
     return (outputDir </> pkgNameRel)
 
 -- | Get the tix file location, given the name of the file (without extension), and the package
@@ -100,8 +100,8 @@ generateHpcReport pkgDir package tests = do
     compilerVersion <- view actualCompilerVersionL
     -- If we're using > GHC 7.10, the hpc 'include' parameter must specify a ghc package key. See
     -- https://github.com/commercialhaskell/stack/issues/785
-    let pkgName' = displayC (packageName package)
-        pkgId = displayC (packageIdentifier package)
+    let pkgName' = T.pack $ packageNameString (packageName package)
+        pkgId = packageIdentifierString (packageIdentifier package)
         ghcVersion = getGhcVersion compilerVersion
         hasLibrary =
           case packageLibraries package of
@@ -234,7 +234,7 @@ generateHpcReportForTargets opts = do
                  case target of
                      TargetAll Dependency -> throwString $
                          "Error: Expected a local package, but " ++
-                         displayC name ++
+                         packageNameString name ++
                          " is either an extra-dep or in the snapshot."
                      TargetComps comps -> do
                          pkgPath <- hpcPkgPath name
@@ -244,7 +244,7 @@ generateHpcReportForTargets opts = do
                                      liftM (pkgPath </>) $ parseRelFile (T.unpack testName ++ "/" ++ T.unpack testName ++ ".tix")
                                  _ -> fail $
                                      "Can't specify anything except test-suites as hpc report targets (" ++
-                                     displayC name ++
+                                     packageNameString name ++
                                      " is used with a non test-suite target)"
                      TargetAll ProjectPackage -> do
                          pkgPath <- hpcPkgPath name
@@ -432,7 +432,7 @@ findPackageFieldForBuiltPackage
 findPackageFieldForBuiltPackage pkgDir pkgId internalLibs field = do
     distDir <- distDirFromDir pkgDir
     let inplaceDir = distDir </> $(mkRelDir "package.conf.inplace")
-        pkgIdStr = displayC pkgId
+        pkgIdStr = packageIdentifierString pkgId
         notFoundErr = return $ Left $ "Failed to find package key for " <> T.pack pkgIdStr
         extractField path = do
             contents <- liftIO $ T.readFile (toFilePath path)
diff --git a/src/Stack/Dot.hs b/src/Stack/Dot.hs
index b5fe391042..9d9936697c 100644
--- a/src/Stack/Dot.hs
+++ b/src/Stack/Dot.hs
@@ -141,7 +141,7 @@ listDependencies opts = do
                   if listDepsLicense opts
                       then maybe "<unknown>" (Text.pack . display . either licenseFromSPDX id) (payloadLicense payload)
                       else maybe "<unknown>" (Text.pack . show) (payloadVersion payload)
-                line = displayC name <> listDepsSep opts <> payloadText
+                line = Text.pack (packageNameString name) <> listDepsSep opts <> payloadText
             in  liftIO $ Text.putStrLn line
 
 -- | @pruneGraph dontPrune toPrune graph@ prunes all packages in
@@ -217,7 +217,7 @@ createDepLoader sourceMap installed globalDumpMap globalIdMap loadPackageDeps pk
           Nothing -> pure (Set.empty, payloadFromInstalled (Map.lookup pkgName installed))
       -- For wired-in-packages, use information from ghc-pkg (see #3084)
       else case Map.lookup pkgName globalDumpMap of
-          Nothing -> error ("Invariant violated: Expected to find wired-in-package " ++ displayC pkgName ++ " in global DB")
+          Nothing -> error ("Invariant violated: Expected to find wired-in-package " ++ packageNameString pkgName ++ " in global DB")
           Just dp -> pure (Set.fromList deps, payloadFromDump dp)
             where
               deps = map (\depId -> maybe (error ("Invariant violated: Expected to find " ++ ghcPkgIdString depId ++ " in global DB"))
@@ -258,7 +258,7 @@ printGraph dotOpts locals graph = do
   void (Map.traverseWithKey printEdges (fst <$> graph))
   liftIO $ Text.putStrLn "}"
   where filteredLocals = Set.filter (\local' ->
-          displayC local' `Set.notMember` dotPrune dotOpts) locals
+          packageNameString local' `Set.notMember` dotPrune dotOpts) locals
 
 -- | Print the local nodes with a different style depending on options
 printLocalNodes :: (F.Foldable t, MonadIO m)
@@ -289,7 +289,7 @@ printEdge from to' = liftIO $ Text.putStrLn (Text.concat [ nodeName from, " -> "
 
 -- | Convert a package name to a graph node name.
 nodeName :: PackageName -> Text
-nodeName name = "\"" <> displayC name <> "\""
+nodeName name = "\"" <> Text.pack (packageNameString name) <> "\""
 
 -- | Print a node with no dependencies
 printLeaf :: MonadIO m => PackageName -> m ()
diff --git a/src/Stack/GhcPkg.hs b/src/Stack/GhcPkg.hs
index 818e3bb17c..99f3129d20 100644
--- a/src/Stack/GhcPkg.hs
+++ b/src/Stack/GhcPkg.hs
@@ -146,7 +146,7 @@ findGhcPkgVersion :: (HasProcessContext env, HasLogFunc env)
                   -> PackageName
                   -> RIO env (Maybe Version)
 findGhcPkgVersion wc pkgDbs name = do
-    mv <- findGhcPkgField wc pkgDbs (displayC name) "version"
+    mv <- findGhcPkgField wc pkgDbs (packageNameString name) "version"
     case mv of
         Just !v -> return (parseVersion $ T.unpack v)
         _ -> return Nothing
@@ -168,7 +168,7 @@ unregisterGhcPkgId wc cv pkgDb gid ident = do
     args = "unregister" : "--user" : "--force" :
         (case cv of
             ACGhc v | v < $(mkVersion "7.9") ->
-                [displayC ident]
+                [packageIdentifierString ident]
             _ -> ["--ipid", ghcPkgIdString gid])
 
 -- | Get the version of Cabal from the global package database.
diff --git a/src/Stack/Ghci.hs b/src/Stack/Ghci.hs
index e6978199cf..4d899cd3d1 100644
--- a/src/Stack/Ghci.hs
+++ b/src/Stack/Ghci.hs
@@ -176,7 +176,7 @@ ghci opts@GhciOpts{..} = do
               figureOutMainFile bopts mainIsTargets localTargets pkgs0
     -- Build required dependencies and setup local packages.
     stackYaml <- view stackYamlL
-    buildDepsAndInitialSteps opts (map (displayC . fst) localTargets)
+    buildDepsAndInitialSteps opts (map (T.pack . packageNameString . fst) localTargets)
     targetWarnings stackYaml localTargets nonLocalTargets mfileTargets
     -- Load the list of modules _after_ building, to catch changes in
     -- unlisted dependencies (#1180)
@@ -293,7 +293,7 @@ getAllLocalTargets GhciOpts{..} targets0 mainIsTargets sourceMap = do
         then return directlyWanted
         else do
             let extraList =
-                  mconcat $ intersperse ", " (map (displayC . fst) extraLoadDeps)
+                  mconcat $ intersperse ", " (map (fromString . packageNameString . fst) extraLoadDeps)
             if ghciLoadLocalDeps
                 then logInfo $
                   "The following libraries will also be loaded into GHCi because " <>
@@ -362,7 +362,7 @@ runGhci GhciOpts{..} targets mainFile pkgs extraFiles exposePackages = do
               -- is because it tries to use the interpreter to set
               -- buffering options on standard IO.
               (if null targets then ["-package", "base"] else []) ++
-              concatMap (\n -> ["-package", displayC n]) exposePackages
+              concatMap (\n -> ["-package", packageNameString n]) exposePackages
             else []
         oneWordOpts bio
             | shouldHidePackages = bioOneWordOpts bio ++ bioPackageFlags bio
@@ -386,7 +386,7 @@ runGhci GhciOpts{..} targets mainFile pkgs extraFiles exposePackages = do
             , "-hidir=" <> toFilePathNoTrailingSep oiDir ]
     logInfo $
       "Configuring GHCi with the following packages: " <>
-      mconcat (intersperse ", " (map (displayC . ghciPkgName) pkgs))
+      mconcat (intersperse ", " (map (fromString . packageNameString . ghciPkgName) pkgs))
     let execGhci extras = do
             menv <- liftIO $ configProcessContextSettings config defaultEnvSettings
             withProcessContext menv $ exec
@@ -543,7 +543,7 @@ figureOutMainFile bopts mainIsTargets targets0 packages = do
     renderCandidate c@(pkgName,namedComponent,mainIs) =
         let candidateIndex = T.pack . show . (+1) . fromMaybe 0 . elemIndex c
         in  candidateIndex candidates <> ". Package `" <>
-            displayC pkgName <>
+            T.pack (packageNameString pkgName) <>
             "' component " <>
             renderComp namedComponent <>
             " with main-is file: " <>
@@ -576,9 +576,9 @@ figureOutMainFile bopts mainIsTargets targets0 packages = do
             CTest name -> "test:" <> name
             CBench name -> "bench:" <> name
     sampleTargetArg (pkg,comp,_) =
-        displayC pkg <> ":" <> renderComp comp
+        T.pack (packageNameString pkg) <> ":" <> renderComp comp
     sampleMainIsArg (pkg,comp,_) =
-        "--main-is " <> displayC pkg <> ":" <> renderComp comp
+        "--main-is " <> T.pack (packageNameString pkg) <> ":" <> renderComp comp
 
 loadGhciPkgDescs
     :: HasEnvConfig env
@@ -618,7 +618,7 @@ loadGhciPkgDesc buildOptsCLI name cabalfp target = do
 
     -- Source the package's *.buildinfo file created by configure if any. See
     -- https://www.haskell.org/cabal/users-guide/developing-packages.html#system-dependent-parameters
-    buildinfofp <- parseRelFile (displayC name ++ ".buildinfo")
+    buildinfofp <- parseRelFile (packageNameString name ++ ".buildinfo")
     hasDotBuildinfo <- doesFileExist (parent cabalfp </> buildinfofp)
     let mbuildinfofp
           | hasDotBuildinfo = Just (parent cabalfp </> buildinfofp)
@@ -820,7 +820,7 @@ targetWarnings stackYaml localTargets nonLocalTargets mfileTargets = do
   unless (null nonLocalTargets) $
     prettyWarnL
       [ flow "Some targets"
-      , parens $ fillSep $ punctuate "," $ map (style Good . displayC) nonLocalTargets
+      , parens $ fillSep $ punctuate "," $ map (style Good . fromString . packageNameString) nonLocalTargets
       , flow "are not local packages, and so cannot be directly loaded."
       , flow "In future versions of stack, this might be supported - see"
       , style Url "https://github.com/commercialhaskell/stack/issues/1441"
diff --git a/src/Stack/Hoogle.hs b/src/Stack/Hoogle.hs
index 310fe6ce8e..dd83b3b694 100644
--- a/src/Stack/Hoogle.hs
+++ b/src/Stack/Hoogle.hs
@@ -95,11 +95,11 @@ hoogleCmd (args,setup,rebuild,startServer) go = withBuildConfig go $ do
         case hooglePackageIdentifier of
             Left{} -> logInfo $
               "Minimum " <>
-              displayC hoogleMinIdent <>
+              fromString (packageIdentifierString hoogleMinIdent) <>
               " is not in your index. Installing the minimum version."
             Right ident -> logInfo $
               "Minimum version is " <>
-              displayC hoogleMinIdent <>
+              fromString (packageIdentifierString hoogleMinIdent) <>
               ". Found acceptable " <>
               display ident <>
               " in your index, installing it."
@@ -117,7 +117,7 @@ hoogleCmd (args,setup,rebuild,startServer) go = withBuildConfig go $ do
                                 { boptsCLITargets =
                                     pure $
                                     either
-                                     displayC
+                                     (T.pack . packageIdentifierString)
                                      (utf8BuilderToText . display)
                                      hooglePackageIdentifier
                                 }))
@@ -167,7 +167,7 @@ hoogleCmd (args,setup,rebuild,startServer) go = withBuildConfig go $ do
                                 [ "Installed Hoogle is too old, "
                                 , T.pack hooglePath
                                 , " is version "
-                                , displayC ver
+                                , T.pack $ versionString ver
                                 , " but >= 5.0 is required."
                                 ]
         case eres of
diff --git a/src/Stack/IDE.hs b/src/Stack/IDE.hs
index b978677e23..03bceec4ed 100644
--- a/src/Stack/IDE.hs
+++ b/src/Stack/IDE.hs
@@ -27,7 +27,7 @@ listPackages = do
     packageDirs <- liftM (map lpvRoot . Map.elems . lpProject) getLocalPackages
     forM_ packageDirs $ \dir -> do
         (gpd, _) <- loadCabalFilePath dir NoPrintWarnings
-        (logInfo . displayC) (gpdPackageName gpd)
+        (logInfo . fromString . packageNameString) (gpdPackageName gpd)
 
 -- | List the targets in the current project.
 listTargets :: HasEnvConfig env => RIO env ()
diff --git a/src/Stack/Init.hs b/src/Stack/Init.hs
index 69254ba03a..b67bb38a78 100644
--- a/src/Stack/Init.hs
+++ b/src/Stack/Init.hs
@@ -393,13 +393,13 @@ getWorkingResolverPlan whichCmd initOpts bundle sd = do
 
                         if length ignored > 1 then do
                           logWarn "*** Ignoring packages:"
-                          logWarn $ display $ indent $ showItems $ map displayC ignored
+                          logWarn $ display $ indent $ showItems $ map packageNameString ignored
                         else
                           logWarn $ "*** Ignoring package: "
-                                 <> displayC
+                                 <> fromString
                                       (case ignored of
                                         [] -> error "getWorkingResolverPlan.head"
-                                        x:_ -> x)
+                                        x:_ -> packageNameString x)
 
                         go available
                     where
diff --git a/src/Stack/New.hs b/src/Stack/New.hs
index 1cef4c02a9..b7a1fb664c 100644
--- a/src/Stack/New.hs
+++ b/src/Stack/New.hs
@@ -65,7 +65,7 @@ new opts forceOverwrite = do
       throwM $ Can'tUseWiredInName (newOptsProjectName opts)
     pwd <- getCurrentDir
     absDir <- if bare then return pwd
-                      else do relDir <- parseRelDir (displayC project)
+                      else do relDir <- parseRelDir (packageNameString project)
                               liftM (pwd </>) (return relDir)
     exists <- doesDirExist absDir
     configTemplate <- view $ configL.to configDefaultTemplate
@@ -99,7 +99,7 @@ new opts forceOverwrite = do
         logInfo
             (loading <> " template \"" <> display (templateName template) <>
              "\" to create project \"" <>
-             displayC project <>
+             fromString (packageNameString project) <>
              "\" in " <>
              if bare then "the current directory"
                      else fromString (toFilePath (dirname absDir)) <>
@@ -197,9 +197,9 @@ applyTemplate project template nonceParams dir templateText = do
       return $ T.pack . show $ year
     let context = M.unions [nonceParams, nameParams, configParams, yearParam]
           where
-            nameAsVarId = T.replace "-" "_" $ displayC project
-            nameAsModule = T.filter (/= '-') $ T.toTitle $ displayC project
-            nameParams = M.fromList [ ("name", displayC project)
+            nameAsVarId = T.replace "-" "_" $ T.pack $ packageNameString project
+            nameAsModule = T.filter (/= '-') $ T.toTitle $ T.pack $ packageNameString project
+            nameParams = M.fromList [ ("name", T.pack $ packageNameString project)
                                     , ("name-as-varid", nameAsVarId)
                                     , ("name-as-module", nameAsModule) ]
             configParams = configTemplateParams config
@@ -368,7 +368,7 @@ instance Show NewException where
                              "    " <> key <> ": value")
                        (S.toList missingKeys))
             , "Or you can pass each one as parameters like this:"
-            , "stack new " <> displayC name <> " " <>
+            , "stack new " <> packageNameString name <> " " <>
               T.unpack (templateName template) <>
               " " <>
               unwords
@@ -389,4 +389,4 @@ instance Show NewException where
     show (BadTemplatesHelpEncoding url err) =
         "UTF-8 decoding error on template info from\n    " <> url <> "\n\n" <> show err
     show (Can'tUseWiredInName name) =
-        "The name \"" <> displayC name <> "\" is used by GHC wired-in packages, and so shouldn't be used as a package name"
+        "The name \"" <> packageNameString name <> "\" is used by GHC wired-in packages, and so shouldn't be used as a package name"
diff --git a/src/Stack/Options/BuildParser.hs b/src/Stack/Options/BuildParser.hs
index e2036520c6..9a0529fdcb 100644
--- a/src/Stack/Options/BuildParser.hs
+++ b/src/Stack/Options/BuildParser.hs
@@ -89,7 +89,7 @@ targetsParser =
               completer targetCompleter <>
               help ("If none specified, use all local packages. " <>
                     "See https://docs.haskellstack.org/en/v" <>
-                    displayC stackMinorVersion <>
+                    versionString stackMinorVersion <>
                     "/build_command/#target-syntax for details.")))
 
 flagsParser :: Parser (Map.Map (Maybe PackageName) (Map.Map FlagName Bool))
diff --git a/src/Stack/Options/Completion.hs b/src/Stack/Options/Completion.hs
index c2b5bd104f..f8cb6b8489 100644
--- a/src/Stack/Options/Completion.hs
+++ b/src/Stack/Options/Completion.hs
@@ -86,7 +86,7 @@ flagCompleter = buildConfigCompleter $ \input -> do
             $ Map.toList lpvs
         normalFlags
             = concatMap (\(name, lpv) ->
-                map (\fl -> displayC name ++ ":" ++ flagString name fl)
+                map (\fl -> packageNameString name ++ ":" ++ flagString name fl)
                     (C.genPackageFlags (lpvGPD lpv)))
             $ Map.toList lpvs
         flagString name fl =
diff --git a/src/Stack/Options/GhciParser.hs b/src/Stack/Options/GhciParser.hs
index 1e7dad467b..e28249ae66 100644
--- a/src/Stack/Options/GhciParser.hs
+++ b/src/Stack/Options/GhciParser.hs
@@ -20,7 +20,7 @@ ghciOptsParser = GhciOpts
                          completer (targetCompleter <> fileExtCompleter [".hs", ".lhs"]) <>
                          help ("If none specified, use all local packages. " <>
                                "See https://docs.haskellstack.org/en/v" <>
-                               displayC stackMinorVersion <>
+                               versionString stackMinorVersion <>
                                "/build_command/#target-syntax for details. " <>
                                "If a path to a .hs or .lhs file is specified, it will be loaded.")))
              <*> fmap concat (many (argsOption (long "ghci-options" <>
diff --git a/src/Stack/Package.hs b/src/Stack/Package.hs
index aaa17cd48e..1eb48b2cf9 100644
--- a/src/Stack/Package.hs
+++ b/src/Stack/Package.hs
@@ -286,7 +286,7 @@ packageFromPackageDescription packageConfig pkgFlags (PackageDescriptionPair pkg
 
     -- Is the package dependency mentioned here me: either the package
     -- name itself, or the name of one of the sub libraries
-    isMe name' = name' == name || displayC name' `S.member` extraLibNames
+    isMe name' = name' == name || fromString (packageNameString name') `S.member` extraLibNames
 
 -- | Generate GHC options for the package's components, and a list of
 -- options which apply generally to the package, not one specific
@@ -402,9 +402,9 @@ generateBuildInfoOpts BioInput {..} =
         concat
             [ case M.lookup name biInstalledMap of
                 Just (_, Stack.Types.Package.Library _ident ipid _) -> ["-package-id=" <> ghcPkgIdString ipid]
-                _ -> ["-package=" <> displayC name <>
+                _ -> ["-package=" <> packageNameString name <>
                  maybe "" -- This empty case applies to e.g. base.
-                     ((("-" <>) . displayC) . piiVersion)
+                     ((("-" <>) . versionString) . piiVersion)
                      (M.lookup name biSourceMap)]
             | name <- pkgs]
     pkgs =
@@ -1252,7 +1252,7 @@ findCandidate dirs name = do
             DotCabalMain{} -> DotCabalMainPath
             DotCabalFile{} -> DotCabalFilePath
             DotCabalCFile{} -> DotCabalCFilePath
-    paths_pkg pkg = "Paths_" ++ displayC pkg
+    paths_pkg pkg = "Paths_" ++ packageNameString pkg
     makeNameCandidates =
         liftM (nubOrd . concat) (mapM makeDirCandidates dirs)
     makeDirCandidates :: Path Abs Dir
@@ -1348,7 +1348,7 @@ buildLogPath package' msuffix = do
   env <- ask
   let stack = getProjectWorkDir env
   fp <- parseRelFile $ concat $
-    displayC (packageIdentifier package') :
+    packageIdentifierString (packageIdentifier package') :
     maybe id (\suffix -> ("-" :) . (suffix :)) msuffix [".log"]
   return $ stack </> $(mkRelDir "logs") </> fp
 
diff --git a/src/Stack/PackageDump.hs b/src/Stack/PackageDump.hs
index a9433c76ad..7273fbe4e9 100644
--- a/src/Stack/PackageDump.hs
+++ b/src/Stack/PackageDump.hs
@@ -68,7 +68,7 @@ ghcPkgDescribe
     -> [Path Abs Dir] -- ^ if empty, use global
     -> ConduitM Text Void (RIO env) a
     -> RIO env a
-ghcPkgDescribe pkgName' = ghcPkgCmdArgs ["describe", "--simple-output", displayC pkgName']
+ghcPkgDescribe pkgName' = ghcPkgCmdArgs ["describe", "--simple-output", packageNameString pkgName']
 
 -- | Call ghc-pkg and stream to the given @Sink@, for a single database
 ghcPkgCmdArgs
diff --git a/src/Stack/SDist.hs b/src/Stack/SDist.hs
index 20ec6b3db7..bc7c24885f 100644
--- a/src/Stack/SDist.hs
+++ b/src/Stack/SDist.hs
@@ -155,7 +155,7 @@ getSDistTarball mpvpBounds pkgDir = do
             | otherwise = packWith packFileEntry False fp
         isCabalFp fp = toFilePath pkgDir FP.</> fp == toFilePath cabalfp
         tarName = pkgId FP.<.> "tar.gz"
-        pkgId = displayC (packageIdentifier (lpPackage lp))
+        pkgId = packageIdentifierString (packageIdentifier (lpPackage lp))
     dirEntries <- mapM packDir (dirsFromFiles files)
     fileEntries <- mapM packFile files
     mcabalFileRevision <- liftIO (readIORef cabalFileRevisionRef)
@@ -405,7 +405,7 @@ checkPackageInExtractedTarball pkgDir = do
     config  <- getDefaultPackageConfig
     (gdesc, PackageDescriptionPair pkgDesc _) <- readPackageDescriptionDir config pkgDir NoPrintWarnings
     logInfo $
-        "Checking package '" <> displayC name <> "' for common mistakes"
+        "Checking package '" <> fromString (packageNameString name) <> "' for common mistakes"
     let pkgChecks =
           -- MSS 2017-12-12: Try out a few different variants of
           -- pkgDesc to try and provoke an error or warning. I don't
diff --git a/src/Stack/Script.hs b/src/Stack/Script.hs
index 24f8bc6165..b3857d3361 100644
--- a/src/Stack/Script.hs
+++ b/src/Stack/Script.hs
@@ -81,12 +81,12 @@ scriptCmd opts go' = do
                           $ words
                           $ S8.unpack
                           $ S8.concat bss
-            if Set.null $ Set.difference (Set.map displayC targetsSet) installed
+            if Set.null $ Set.difference (Set.map packageNameString targetsSet) installed
                 then logDebug "All packages already installed"
                 else do
                     logDebug "Missing packages, performing installation"
                     Stack.Build.build Nothing lk defaultBuildOptsCLI
-                        { boptsCLITargets = map displayC $ Set.toList targetsSet
+                        { boptsCLITargets = map (T.pack . packageNameString) $ Set.toList targetsSet
                         }
 
         let ghcArgs = concat
@@ -95,7 +95,7 @@ scriptCmd opts go' = do
                 , map (\x -> "-package" ++ x)
                     $ Set.toList
                     $ Set.insert "base"
-                    $ Set.map displayC targetsSet
+                    $ Set.map packageNameString targetsSet
                 , case soCompile opts of
                     SEInterpret -> []
                     SECompile -> []
@@ -147,9 +147,9 @@ getPackagesFromModuleInfo mi scriptFP = do
                                 [pn] -> return $ Set.singleton pn
                                 pns' -> throwString $ concat
                                     [ "Module "
-                                    , displayC mn
+                                    , moduleNameString mn
                                     , " appears in multiple packages: "
-                                    , unwords $ map displayC pns'
+                                    , unwords $ map packageNameString pns'
                                     ]
                         Nothing -> return Set.empty
                 return $ Set.unions pns `Set.difference` blacklist
diff --git a/src/Stack/Setup.hs b/src/Stack/Setup.hs
index cda1d49ec8..1b27a5bb40 100644
--- a/src/Stack/Setup.hs
+++ b/src/Stack/Setup.hs
@@ -197,7 +197,7 @@ instance Show SetupException where
     show (DockerStackExeNotFound stackVersion' osKey) = concat
         [ stackProgName
         , "-"
-        , displayC stackVersion'
+        , versionString stackVersion'
         , " executable not found for "
         , T.unpack osKey
         , "\nUse the '"
@@ -670,7 +670,7 @@ ensureDockerStackExe containerPlatform = do
           "Downloading Docker-compatible " <>
           fromString stackProgName <>
           " executable"
-        sri <- downloadStackReleaseInfo Nothing Nothing (Just (displayC stackMinorVersion))
+        sri <- downloadStackReleaseInfo Nothing Nothing (Just (versionString stackMinorVersion))
         platforms <- runReaderT preferredPlatforms (containerPlatform, PlatformVariantNone)
         downloadStackExe platforms sri stackExeDir False (const $ return ())
     return stackExePath
@@ -692,7 +692,7 @@ upgradeCabal wc upgradeTo = do
             else
                 logInfo $
                   "No install necessary. Cabal " <>
-                  displayC installed <>
+                  fromString (versionString installed) <>
                   " is already installed"
         Latest -> do
           mversion <- getLatestHackageVersion name YesPreferredVersions
@@ -704,9 +704,9 @@ upgradeCabal wc upgradeTo = do
                 else
                     logInfo $
                         "No upgrade necessary: Cabal-" <>
-                        displayC latestVersion <>
+                        fromString (versionString latestVersion) <>
                         " is the same or newer than latest hackage version " <>
-                        displayC installed
+                        fromString (versionString installed)
 
 -- Configure and run the necessary commands for a cabal install
 doCabalInstall :: (HasConfig env, HasGHCVariant env)
@@ -722,18 +722,18 @@ doCabalInstall wc installed wantedVersion = do
     withSystemTempDir "stack-cabal-upgrade" $ \tmpdir -> do
         logInfo $
             "Installing Cabal-" <>
-            displayC wantedVersion <>
+            fromString (versionString wantedVersion) <>
             " to replace " <>
-            displayC installed
+            fromString (versionString installed)
         let name = $(mkPackageName "Cabal")
-        suffix <- parseRelDir $ "Cabal-" ++ displayC wantedVersion
+        suffix <- parseRelDir $ "Cabal-" ++ versionString wantedVersion
         let dir = tmpdir </> suffix
         unpackPackageLocation dir $ PLIHackage
           (PackageIdentifierRevision name wantedVersion CFILatest)
           Nothing
         compilerPath <- findExecutable (compilerExeName wc)
                     >>= either throwM parseAbsFile
-        versionDir <- parseRelDir $ displayC wantedVersion
+        versionDir <- parseRelDir $ versionString wantedVersion
         let installRoot = toFilePath $ parent (parent compilerPath)
                                     </> $(mkRelDir "new-cabal")
                                     </> versionDir
@@ -1091,7 +1091,7 @@ installGHCPosix version downloadInfo _ archiveFile archiveType tempDir destDir =
     dir <-
         liftM (tempDir </>) $
         parseRelDir $
-        "ghc-" ++ displayC version
+        "ghc-" ++ versionString version
 
     let runStep step wd env cmd args = do
             menv' <- modifyEnvVars menv (Map.union env)
@@ -1248,7 +1248,7 @@ ensureGhcjsBooted cv shouldBoot bootOpts = do
                 actualStackYaml <- if stackYamlExists then return stackYaml
                     else
                         liftM ((destDir </> $(mkRelDir "src")) </>) $
-                        parseRelFile $ "ghcjs-" ++ displayC ghcjsVersion ++ "/stack.yaml"
+                        parseRelFile $ "ghcjs-" ++ versionString ghcjsVersion ++ "/stack.yaml"
                 actualStackYamlExists <- doesFileExist actualStackYaml
                 unless actualStackYamlExists $
                     throwString "Error: Couldn't find GHCJS stack.yaml in old or new location."
@@ -1270,20 +1270,20 @@ bootGhcjs ghcjsVersion stackYaml destDir bootOpts =
             | v < $(mkVersion "1.22.4") -> do
                 logInfo $
                     "The cabal-install found on PATH is too old to be used for booting GHCJS (version " <>
-                    displayC v <>
+                    fromString (versionString v) <>
                     ")."
                 return True
             | v >= $(mkVersion "1.23") -> do
                 logWarn $
                     "The cabal-install found on PATH is a version stack doesn't know about, version " <>
-                    displayC v <>
+                    fromString (versionString v) <>
                     ". This may or may not work.\n" <>
                     "See this issue: https://github.com/ghcjs/ghcjs/issues/470"
                 return False
             | ghcjsVersion >= $(mkVersion "0.2.0.20160413") && v >= $(mkVersion "1.22.8") -> do
                 logWarn $
                     "The cabal-install found on PATH, version " <>
-                    displayC v <>
+                    fromString (versionString v) <>
                     ", is >= 1.22.8.\n" <>
                     "That version has a bug preventing ghcjs < 0.2.0.20160413 from booting.\n" <>
                     "See this issue: https://github.com/ghcjs/ghcjs/issues/470"
@@ -1408,7 +1408,7 @@ installGHCWindows :: HasConfig env
                   -> Path Abs Dir
                   -> RIO env ()
 installGHCWindows version si archiveFile archiveType _tempDir destDir = do
-    tarComponent <- parseRelDir $ "ghc-" ++ displayC version
+    tarComponent <- parseRelDir $ "ghc-" ++ versionString version
     withUnpackedTarball7z "GHC" si archiveFile archiveType (Just tarComponent) destDir
     logInfo $ "GHC installed to " <> fromString (toFilePath destDir)
 
diff --git a/src/Stack/Setup/Installed.hs b/src/Stack/Setup/Installed.hs
index bf4ce97589..72d4f8606f 100644
--- a/src/Stack/Setup/Installed.hs
+++ b/src/Stack/Setup/Installed.hs
@@ -45,11 +45,11 @@ data Tool
     | ToolGhcjs ActualCompiler -- ^ e.g. ghcjs-0.1.0_ghc-7.10.2
 
 toolString :: Tool -> String
-toolString (Tool ident) = displayC ident
+toolString (Tool ident) = packageIdentifierString ident
 toolString (ToolGhcjs cv) = compilerVersionString cv
 
 toolNameString :: Tool -> String
-toolNameString (Tool ident) = displayC $ pkgName ident
+toolNameString (Tool ident) = packageNameString $ pkgName ident
 toolNameString ToolGhcjs{} = "ghcjs"
 
 parseToolText :: Text -> Maybe Tool
diff --git a/src/Stack/Sig/Sign.hs b/src/Stack/Sig/Sign.hs
index 7c5c606afe..becfd3e52e 100644
--- a/src/Stack/Sig/Sign.hs
+++ b/src/Stack/Sig/Sign.hs
@@ -96,7 +96,7 @@ signPackage url pkg filePath = do
     let (PackageIdentifier name version) = pkg
     fingerprint <- gpgVerify sig filePath
     let fullUrl =
-            url <> "/upload/signature/" <> displayC name <> "/" <> displayC version <>
+            url <> "/upload/signature/" <> packageNameString name <> "/" <> versionString version <>
             "/" <>
             show fingerprint
     req <- parseUrlThrow fullUrl
diff --git a/src/Stack/Snapshot.hs b/src/Stack/Snapshot.hs
index 0a90a7e74f..19b6c5a400 100644
--- a/src/Stack/Snapshot.hs
+++ b/src/Stack/Snapshot.hs
@@ -72,7 +72,7 @@ instance Show SnapshotException where
     ]
   show (PackageDefinedTwice name loc1 loc2) = concat
     [ "Package "
-    , displayC name
+    , packageNameString name
     , " is defined twice, at "
     , show loc1
     , " and "
@@ -83,19 +83,19 @@ instance Show SnapshotException where
     where
       go (name, deps) = concat
         $ "\n"
-        : displayC name
+        : packageNameString name
         : " is missing:\n"
         : map goDep (Map.toList deps)
 
       goDep (dep, (intervals, mversion)) = concat
         [ "- "
-        , displayC dep
+        , packageNameString dep
         , ". Requires: "
         , display $ toVersionRange intervals
         , ", "
         , case mversion of
             Nothing -> "none present"
-            Just version -> displayC version ++ " found"
+            Just version -> versionString version ++ " found"
         , "\n"
         ]
   show (FilepathInCustomSnapshot url) =
@@ -106,7 +106,7 @@ instance Show SnapshotException where
     T.unpack url
   show (MissingPackages names) =
     "The following packages specified by flags or options are not found: " ++
-    unwords (map displayC (Set.toList names))
+    unwords (map packageNameString (Set.toList names))
   show (CustomResolverException url loc e) = concat
     [ "Unable to load custom resolver "
     , T.unpack url
@@ -360,7 +360,8 @@ fromGlobalHints =
       -- project compatibility.
       , lpiLocation = either impureThrow id
                     $ parseGhcPkgId
-                    $ displayC
+                    $ fromString
+                    $ packageIdentifierString
                     $ PackageIdentifier name ver
       , lpiFlags = Map.empty
       , lpiGhcOptions = []
diff --git a/src/Stack/Solver.hs b/src/Stack/Solver.hs
index 2be8141523..526ce2e360 100644
--- a/src/Stack/Solver.hs
+++ b/src/Stack/Solver.hs
@@ -135,7 +135,7 @@ cabalSolver cabalfps constraintType
 
             when (any isNothing mPkgNames) $ do
                   logInfo $ "*** Only some package names could be parsed: " <>
-                      mconcat (intersperse ", " (map displayC pkgNames))
+                      mconcat (intersperse ", " (map (fromString . packageNameString) pkgNames))
                   error $ T.unpack $
                        "*** User packages involved in cabal failure: "
                        <> T.intercalate ", " (parseConflictingPkgs msg)
@@ -176,7 +176,7 @@ cabalSolver cabalfps constraintType
     formatFlagConstraint package flag enabled =
         let sign = if enabled then '+' else '-'
         in
-        "--constraint=" ++ unwords [displayC package, sign : displayC flag]
+        "--constraint=" ++ unwords [packageNameString package, sign : flagNameString flag]
 
     -- Note the order of the Map union is important
     -- We override a package in snapshot by a src package
@@ -237,15 +237,15 @@ getCabalConfig dir constraintType constraints = do
     return $ cache : remote : map goConstraint (Map.toList constraints)
   where
     goConstraint (name, version) =
-        assert (not . T.null . displayC $ version) $
+        assert (not . null . versionString $ version) $
             T.concat
               [ if constraintType == Constraint
                    || name `Set.member` wiredInPackages
                 then "constraint: "
                 else "preference: "
-              , displayC name
+              , T.pack $ packageNameString name
               , "=="
-              , displayC version
+              , T.pack $ versionString version
               ]
 
 setupCompiler
@@ -300,12 +300,12 @@ setupCabalEnv compiler inner = do
         Just version
             | version < $(mkVersion "1.24") -> prettyWarn $
                 "Installed version of cabal-install (" <>
-                displayC version <>
+                fromString (versionString version) <>
                 ") doesn't support custom-setup clause, and so may not yield correct results." <> line <>
                 "To resolve this, install a newer version via 'stack install cabal-install'." <> line
             | version >= $(mkVersion "1.25") -> prettyWarn $
                 "Installed version of cabal-install (" <>
-                displayC version <>
+                fromString (versionString version) <>
                 ") is newer than stack has been tested with.  If you run into difficulties, consider downgrading." <> line
             | otherwise -> return ()
 
@@ -539,7 +539,7 @@ cabalPackagesCheck cabaldirs noPkgMsg dupErrMsg = do
 
     let normalizeString = T.unpack . T.normalize T.NFC . T.pack
         getNameMismatchPkg (fp, gpd)
-            | (normalizeString . displayC . gpdPackageName) gpd /= (normalizeString . FP.takeBaseName . toFilePath) fp
+            | (normalizeString . packageNameString . gpdPackageName) gpd /= (normalizeString . FP.takeBaseName . toFilePath) fp
                 = Just fp
             | otherwise = Nothing
         nameMismatchPkgs = mapMaybe getNameMismatchPkg packages
diff --git a/src/Stack/Types/Build.hs b/src/Stack/Types/Build.hs
index 8f75f173de..c01d8153c7 100644
--- a/src/Stack/Types/Build.hs
+++ b/src/Stack/Types/Build.hs
@@ -138,9 +138,9 @@ data UnusedFlags = UFNoPackage FlagSource PackageName
 
 instance Show StackBuildException where
     show (Couldn'tFindPkgId name) =
-              "After installing " <> displayC name <>
+              "After installing " <> packageNameString name <>
                ", the package id couldn't be found " <> "(via ghc-pkg describe " <>
-               displayC name <> "). This shouldn't happen, " <>
+               packageNameString name <> "). This shouldn't happen, " <>
                "please report as a bug"
     show (CompilerVersionMismatch mactual (expected, earch) ghcVariant ghcBuild check mstack resolution) = concat
                 [ case mactual of
@@ -179,9 +179,9 @@ instance Show StackBuildException where
             | Set.null noKnown = []
             | otherwise = return $
                 "The following target packages were not found: " ++
-                intercalate ", " (map displayC $ Set.toList noKnown) ++
+                intercalate ", " (map packageNameString $ Set.toList noKnown) ++
                 "\nSee https://docs.haskellstack.org/en/v"
-                <> displayC stackMinorVersion <>
+                <> versionString stackMinorVersion <>
                 "/build_command/#target-syntax for details."
         notInSnapshot'
             | Map.null notInSnapshot = []
@@ -193,11 +193,11 @@ instance Show StackBuildException where
                 : "but there's no guarantee that they'll build together)."
                 : ""
                 : map
-                    (\(name, version') -> "- " ++ displayC
+                    (\(name, version') -> "- " ++ packageIdentifierString
                         (PackageIdentifier name version'))
                     (Map.toList notInSnapshot)
     show (TestSuiteFailure ident codes mlogFile bs) = unlines $ concat
-        [ ["Test suite failure for package " ++ displayC ident]
+        [ ["Test suite failure for package " ++ packageIdentifierString ident]
         , flip map (Map.toList codes) $ \(name, mcode) -> concat
             [ "    "
             , T.unpack name
@@ -227,11 +227,11 @@ instance Show StackBuildException where
     show (ExecutionFailure es) = intercalate "\n\n" $ map show es
     show (LocalPackageDoesn'tMatchTarget name localV requestedV) = concat
         [ "Version for local package "
-        , displayC name
+        , packageNameString name
         , " is "
-        , displayC localV
+        , versionString localV
         , ", but you asked for "
-        , displayC requestedV
+        , versionString requestedV
         , " on the command line"
         ]
     show (NoSetupHsFound dir) =
@@ -247,7 +247,7 @@ instance Show StackBuildException where
         go :: UnusedFlags -> String
         go (UFNoPackage src name) = concat
             [ "- Package '"
-            , displayC name
+            , packageNameString name
             , "' not found"
             , showFlagSrc src
             ]
@@ -258,18 +258,18 @@ instance Show StackBuildException where
             , showFlagSrc src
             , ":\n"
             , intercalate "\n"
-                          (map (\flag -> "  " ++ displayC flag)
+                          (map (\flag -> "  " ++ flagNameString flag)
                                (Set.toList flags))
             , "\n- Flags defined by package '" ++ name ++ "':\n"
             , intercalate "\n"
-                          (map (\flag -> "  " ++ name ++ ":" ++ displayC flag)
+                          (map (\flag -> "  " ++ name ++ ":" ++ flagNameString flag)
                                (Set.toList pkgFlags))
             ]
-          where name = displayC (packageName pkg)
+          where name = packageNameString (packageName pkg)
                 pkgFlags = packageDefinedFlags pkg
         go (UFSnapshot name) = concat
             [ "- Attempted to set flag on snapshot package "
-            , displayC name
+            , packageNameString name
             , ", please add to extra-deps"
             ]
     show (TargetParseException [err]) = "Error parsing targets: " ++ T.unpack err
@@ -308,7 +308,7 @@ instance Show StackBuildException where
     show (ConstructPlanFailed msg) = msg
     show (LocalPackagesPresent locals) = unlines
       $ "Local packages are not allowed when using the script command. Packages found:"
-      : map (\ident -> "- " ++ displayC ident) locals
+      : map (\ident -> "- " ++ packageIdentifierString ident) locals
 
 missingExeError :: Bool -> String -> String
 missingExeError isSimpleBuildType msg =
@@ -342,9 +342,9 @@ showBuildError isBuildingSetup exitCode mtaskProvides execName fullArgs logFiles
   in "\n--  While building " ++
      (case (isBuildingSetup, mtaskProvides) of
        (False, Nothing) -> error "Invariant violated: unexpected case in showBuildError"
-       (False, Just taskProvides') -> "package " ++ dropQuotes (displayC taskProvides')
+       (False, Just taskProvides') -> "package " ++ dropQuotes (packageIdentifierString taskProvides')
        (True, Nothing) -> "simple Setup.hs"
-       (True, Just taskProvides') -> "custom Setup.hs for package " ++ dropQuotes (displayC taskProvides')
+       (True, Just taskProvides') -> "custom Setup.hs for package " ++ dropQuotes (packageIdentifierString taskProvides')
      ) ++
      " using:\n      " ++ fullCmd ++ "\n" ++
      "    Process exited with code: " ++ show exitCode ++
@@ -566,7 +566,7 @@ configureOptsDirs bco loc package = concat
             Nothing -> installRoot </> docDirSuffix
             Just dir -> installRoot </> docDirSuffix </> dir
     pkgVerDir =
-        parseRelDir (displayC (PackageIdentifier (packageName package)
+        parseRelDir (packageIdentifierString (PackageIdentifier (packageName package)
                                                                 (packageVersion package)) ++
                      [pathSeparator])
 
@@ -591,7 +591,7 @@ configureOptsNoDir econfig bco deps isLocal package = concat
                        (if enabled
                            then ""
                            else "-") <>
-                       displayC name)
+                       flagNameString name)
                     (Map.toList flags)
     , concatMap (\x -> [compilerOptionsCabalFlag wc, T.unpack x]) (packageGhcOptions package)
     , map ("--extra-include-dirs=" ++) (Set.toList (configExtraIncludeDirs config))
@@ -623,16 +623,16 @@ configureOptsNoDir econfig bco deps isLocal package = concat
 
     toDepOption1_22 (PackageIdentifier name _) gid = concat
         [ "--dependency="
-        , displayC name
+        , packageNameString name
         , "="
         , ghcPkgIdString gid
         ]
 
     toDepOption1_18 ident _gid = concat
         [ "--constraint="
-        , displayC name
+        , packageNameString name
         , "=="
-        , displayC version'
+        , versionString version'
         ]
       where
         PackageIdentifier name version' = ident
diff --git a/src/Stack/Types/Config.hs b/src/Stack/Types/Config.hs
index 4ef5755dc1..fbd7ba9e65 100644
--- a/src/Stack/Types/Config.hs
+++ b/src/Stack/Types/Config.hs
@@ -1140,7 +1140,7 @@ instance Show ConfigException where
       where
         go (name, dirs) = unlines
             $ ""
-            : (displayC name ++ " used in:")
+            : (packageNameString name ++ " used in:")
             : map goLoc dirs
         goLoc loc = "- " ++ show loc
 instance Exception ConfigException
@@ -1324,7 +1324,7 @@ compilerVersionDir :: (MonadThrow m, MonadReader env m, HasEnvConfig env) => m (
 compilerVersionDir = do
     compilerVersion <- view actualCompilerVersionL
     parseRelDir $ case compilerVersion of
-        ACGhc version -> displayC version
+        ACGhc version -> versionString version
         ACGhcjs {} -> compilerVersionString compilerVersion
 
 -- | Package database for installing dependencies into
diff --git a/src/Stack/Types/Docker.hs b/src/Stack/Types/Docker.hs
index 595b85c9cb..d87bbc1a23 100644
--- a/src/Stack/Types/Docker.hs
+++ b/src/Stack/Types/Docker.hs
@@ -278,19 +278,19 @@ instance Show StackDockerException where
                ,"your configuration file."]
     show (DockerTooOldException minVersion haveVersion) =
         concat ["Minimum docker version '"
-               ,displayC minVersion
+               ,versionString minVersion
                ,"' is required by "
                ,stackProgName
                ," (you have '"
-               ,displayC haveVersion
+               ,versionString haveVersion
                ,"')."]
     show (DockerVersionProhibitedException prohibitedVersions haveVersion) =
         concat ["These Docker versions are incompatible with "
                ,stackProgName
                ," (you have '"
-               ,displayC haveVersion
+               ,versionString haveVersion
                ,"'): "
-               ,intercalate ", " (map displayC prohibitedVersions)
+               ,intercalate ", " (map versionString prohibitedVersions)
                ,"."]
     show (BadDockerVersionException requiredRange haveVersion) =
         concat ["The version of 'docker' you are using ("
@@ -305,23 +305,23 @@ instance Show StackDockerException where
         concat ["The host's version of '"
                ,stackProgName
                ,"' is too old for this Docker image.\nVersion "
-               ,displayC minVersion
+               ,versionString minVersion
                ," is required; you have "
-               ,displayC hostVersion
+               ,versionString hostVersion
                ,"."]
     show (HostStackTooOldException minVersion Nothing) =
         concat ["The host's version of '"
                ,stackProgName
                ,"' is too old.\nVersion "
-               ,displayC minVersion
+               ,versionString minVersion
                ," is required."]
     show (ContainerStackTooOldException requiredVersion containerVersion) =
         concat ["The Docker container's version of '"
                ,stackProgName
                ,"' is too old.\nVersion "
-               ,displayC requiredVersion
+               ,versionString requiredVersion
                ," is required; the container has "
-               ,displayC containerVersion
+               ,versionString containerVersion
                ,"."]
     show CannotDetermineProjectRootException =
         "Cannot determine project root directory for Docker sandbox."
diff --git a/src/Stack/Types/NamedComponent.hs b/src/Stack/Types/NamedComponent.hs
index 7cd83531da..3b360f0a12 100644
--- a/src/Stack/Types/NamedComponent.hs
+++ b/src/Stack/Types/NamedComponent.hs
@@ -41,7 +41,7 @@ renderPkgComponents :: [(PackageName, NamedComponent)] -> Text
 renderPkgComponents = T.intercalate " " . map renderPkgComponent
 
 renderPkgComponent :: (PackageName, NamedComponent) -> Text
-renderPkgComponent (pkg, comp) = displayC pkg <> ":" <> renderComponent comp
+renderPkgComponent (pkg, comp) = fromString (packageNameString pkg) <> ":" <> renderComponent comp
 
 exeComponents :: Set NamedComponent -> Set Text
 exeComponents = Set.fromList . mapMaybe mExeName . Set.toList
diff --git a/src/Stack/Types/Package.hs b/src/Stack/Types/Package.hs
index c36cf7d6cc..73656b60bd 100644
--- a/src/Stack/Types/Package.hs
+++ b/src/Stack/Types/Package.hs
@@ -76,7 +76,7 @@ instance Show PackageException where
     show (MismatchedCabalIdentifier pir ident) = concat
         [ "Mismatched package identifier."
         , "\nFound:    "
-        , displayC ident
+        , packageIdentifierString ident
         , "\nExpected: "
         , T.unpack $ utf8BuilderToText $ display pir
         ]
diff --git a/src/Stack/Unpack.hs b/src/Stack/Unpack.hs
index d91bb27d83..4456f14693 100644
--- a/src/Stack/Unpack.hs
+++ b/src/Stack/Unpack.hs
@@ -44,7 +44,7 @@ unpackPackages mSnapshotDef dest input = do
       errs -> throwM $ CouldNotParsePackageSelectors errs
     locs <- Map.fromList <$> mapM
           (\(pir, ident) -> do
-              suffix <- parseRelDir $ displayC ident
+              suffix <- parseRelDir $ packageIdentifierString ident
               pure (pir, dest </> suffix)
           )
           (map (\pir@(PackageIdentifierRevision name ver _) ->
@@ -73,7 +73,7 @@ unpackPackages mSnapshotDef dest input = do
         case mver1 of
           Just _ -> pure mver1
           Nothing -> do
-            updated <- updateHackageIndex $ Just $ "Could not find package " <> displayC name <> ", updating"
+            updated <- updateHackageIndex $ Just $ "Could not find package " <> fromString (packageNameString name) <> ", updating"
             case updated of
               YesUpdateOccurred -> getLatestHackageVersion name YesPreferredVersions
               NoUpdateOccurred -> pure Nothing
@@ -82,11 +82,11 @@ unpackPackages mSnapshotDef dest input = do
           candidates <- getHackageTypoCorrections name
           pure $ Left $ concat
             [ "Could not find package "
-            , displayC name
+            , packageNameString name
             , " on Hackage"
             , if null candidates
                 then ""
-                else ". Perhaps you meant: " ++ intercalate ", " (map displayC candidates)
+                else ". Perhaps you meant: " ++ intercalate ", " (map packageNameString candidates)
             ]
         Just pir@(PackageIdentifierRevision _ ver _) -> pure $ Right
           ( PLIHackage pir Nothing
@@ -97,7 +97,7 @@ unpackPackages mSnapshotDef dest input = do
     toLocSnapshot sd name =
         go $ concatMap snapshotLocations $ sdSnapshots sd
       where
-        go [] = pure $ Left $ "Package does not appear in snapshot: " ++ displayC name
+        go [] = pure $ Left $ "Package does not appear in snapshot: " ++ packageNameString name
         go (loc:locs) = do
           ident@(PackageIdentifier name' _) <- getPackageLocationIdent loc
           if name == name'
diff --git a/src/Stack/Upgrade.hs b/src/Stack/Upgrade.hs
index bb385ffc74..905a430141 100644
--- a/src/Stack/Upgrade.hs
+++ b/src/Stack/Upgrade.hs
@@ -148,9 +148,9 @@ binaryUpgrade (BinaryOpts mplatform force' mver morg mrepo) = do
             Just downloadVersion -> do
                 prettyInfoL
                     [ flow "Current Stack version:"
-                    , displayC stackVersion <> ","
+                    , fromString (versionString stackVersion) <> ","
                     , flow "available download version:"
-                    , displayC downloadVersion
+                    , fromString (versionString downloadVersion)
                     ]
                 return $ downloadVersion > stackVersion
 
@@ -229,7 +229,7 @@ sourceUpgrade gConfigMonoid mresolver builtHash (SourceOpts gitRepo) =
                 prettyInfoS "Already at latest version, no upgrade required"
                 return Nothing
             else do
-                suffix <- parseRelDir $ "stack-" ++ displayC version
+                suffix <- parseRelDir $ "stack-" ++ versionString version
                 let dir = tmp </> suffix
                 unpackPackageLocation dir $ PLIHackage pir Nothing
                 pure $ Just dir
diff --git a/src/Stack/Upload.hs b/src/Stack/Upload.hs
index 5027a700fc..db0e5ca25e 100644
--- a/src/Stack/Upload.hs
+++ b/src/Stack/Upload.hs
@@ -179,9 +179,9 @@ uploadRevision baseUrl creds ident@(PackageIdentifier name _) cabalFile = do
   req0 <- parseRequest $ concat
     [ baseUrl
     , "package/"
-    , displayC ident
+    , packageIdentifierString ident
     , "/"
-    , displayC name
+    , packageNameString name
     , ".cabal/edit"
     ]
   req1 <- formDataBody
diff --git a/subs/curator/src/Curator/Snapshot.hs b/subs/curator/src/Curator/Snapshot.hs
index 202f0f4634..6b3bf8695b 100644
--- a/subs/curator/src/Curator/Snapshot.hs
+++ b/subs/curator/src/Curator/Snapshot.hs
@@ -41,19 +41,19 @@ toLoc name pc =
   case pcSource pc of
     PSHackage (HackageSource mrange mrequiredLatest revisions) -> do
       versions <- getHackagePackageVersions NoPreferredVersions name -- don't follow the preferred versions on Hackage, give curators more control
-      when (Map.null versions) $ error $ "Package not found on Hackage: " ++ displayC name
+      when (Map.null versions) $ error $ "Package not found on Hackage: " ++ packageNameString name
       for_ mrequiredLatest $ \required ->
         case Map.maxViewWithKey versions of
-          Nothing -> error $ "No versions found for " ++ displayC name
+          Nothing -> error $ "No versions found for " ++ packageNameString name
           Just ((version, _), _)
             | version == required -> pure ()
             | otherwise -> error $ concat
                 [ "For package "
-                , displayC name
+                , fromString (packageNameString name)
                 , ", required latest version to be "
-                , displayC required
+                , fromString (versionString required)
                 , ", but actual latest is "
-                , displayC version
+                , fromString (versionString version)
                 ]
       let versions' =
             case mrange of
diff --git a/subs/curator/src/Curator/Unpack.hs b/subs/curator/src/Curator/Unpack.hs
index 28f68ddbea..19bcc5ed72 100644
--- a/subs/curator/src/Curator/Unpack.hs
+++ b/subs/curator/src/Curator/Unpack.hs
@@ -29,15 +29,15 @@ unpackSnapshot cons snap root = do
     PackageIdentifier name version <- getPackageLocationIdent pl
     pc <-
       case Map.lookup name $ consPackages cons of
-        Nothing -> error $ "Package not found in constraints: " ++ displayC name
+        Nothing -> error $ "Package not found in constraints: " ++ packageNameString name
         Just pc -> pure pc
     if pcSkipBuild pc
       then pure mempty
       else do
         let suffixBuilder =
-              displayC name <>
+              fromString (packageNameString name) <>
               "-" <>
-              displayC version <>
+              fromString (versionString version) <>
               "@" <>
               display sha
         suffixTmp <- parseRelDir $ T.unpack $ utf8BuilderToText $ suffixBuilder <> ".tmp"
@@ -67,7 +67,7 @@ unpackSnapshot cons snap root = do
   stackYaml <- parseRelFile "stack.yaml"
   let stackYamlFP = toFilePath $ root </> stackYaml
   liftIO $ encodeFile stackYamlFP $ object
-    [ "resolver" .= ("ghc-" ++ displayC (consGhcVersion cons))
+    [ "resolver" .= ("ghc-" ++ versionString (consGhcVersion cons))
     , "packages" .= Set.map (\suffix -> toFilePath (unpacked </> suffix)) suffixes
     , "flags" .= fmap toCabalStringMap (toCabalStringMap flags)
     , "curator" .= object
diff --git a/subs/pantry/src/Pantry.hs b/subs/pantry/src/Pantry.hs
index 15378b054a..ddfe730f9a 100644
--- a/subs/pantry/src/Pantry.hs
+++ b/subs/pantry/src/Pantry.hs
@@ -96,7 +96,11 @@ module Pantry
   , nightlySnapshotLocation
 
     -- * Cabal helpers
-  , displayC -- FIXME remove
+  , packageIdentifierString
+  , packageNameString
+  , flagNameString
+  , versionString
+  , moduleNameString
   , CabalString (..)
   , toCabalStringMap
   , unCabalStringMap
diff --git a/subs/pantry/src/Pantry/Hackage.hs b/subs/pantry/src/Pantry/Hackage.hs
index 08a631d142..afdc3d5dff 100644
--- a/subs/pantry/src/Pantry/Hackage.hs
+++ b/subs/pantry/src/Pantry/Hackage.hs
@@ -381,8 +381,10 @@ getHackageTypoCorrections
   -> RIO env [PackageName]
 getHackageTypoCorrections name1 =
     withStorage $ sinkHackagePackageNames
-      (\name2 -> damerauLevenshtein (displayC name1) (displayC name2) < 4)
+      (\name2 -> name1 `distance` name2 < 4)
       (takeC 10 .| sinkList)
+    where
+      distance = damerauLevenshtein `on` (T.pack . packageNameString)
 
 -- | Should we pay attention to Hackage's preferred versions?
 --
@@ -406,7 +408,7 @@ getHackagePackageVersions usePreferred name = withStorage $ do
   let predicate :: Version -> Map Revision BlobKey -> Bool
       predicate = fromMaybe (\_ _ -> True) $ do
         preferredT1 <- mpreferred
-        preferredT2 <- T.stripPrefix (displayC name) preferredT1
+        preferredT2 <- T.stripPrefix (T.pack $ packageNameString name) preferredT1
         vr <- Distribution.Text.simpleParse $ T.unpack preferredT2
         Just $ \v _ -> withinRange v vr
   Map.filterWithKey predicate <$> loadHackagePackageVersions name
diff --git a/subs/pantry/src/Pantry/Types.hs b/subs/pantry/src/Pantry/Types.hs
index 7f4c61079b..17f7805c66 100644
--- a/subs/pantry/src/Pantry/Types.hs
+++ b/subs/pantry/src/Pantry/Types.hs
@@ -50,7 +50,11 @@ module Pantry.Types
   , parsePackageName
   , parseFlagName
   , parseVersion
-  , displayC
+  , packageIdentifierString
+  , packageNameString
+  , flagNameString
+  , versionString
+  , moduleNameString
   , OptionalSubdirs (..)
   , ArchiveLocation (..)
   , RelFilePath (..)
@@ -98,9 +102,9 @@ import qualified Pantry.SHA256 as SHA256
 import qualified Distribution.Compat.ReadP as Parse
 import Distribution.CabalSpecVersion (CabalSpecVersion (..), cabalSpecLatest)
 import Distribution.Parsec.Common (PError (..), PWarning (..), showPos)
-import Distribution.Types.PackageName (PackageName)
+import Distribution.Types.PackageName (PackageName, unPackageName)
 import Distribution.Types.VersionRange (VersionRange)
-import Distribution.PackageDescription (FlagName, GenericPackageDescription)
+import Distribution.PackageDescription (FlagName, unFlagName, GenericPackageDescription)
 import Distribution.Types.PackageId (PackageIdentifier (..))
 import qualified Distribution.Text
 import Distribution.ModuleName (ModuleName)
@@ -144,7 +148,7 @@ data Package = Package
 
 cabalFileName :: PackageName -> SafeFilePath
 cabalFileName name =
-  case mkSafeFilePath $ displayC name <> ".cabal" of
+  case mkSafeFilePath $ T.pack (packageNameString name) <> ".cabal" of
     Nothing -> error $ "cabalFileName: failed for " ++ show name
     Just sfp -> sfp
 
@@ -437,7 +441,7 @@ instance FromJSON BlobKey where
 
 newtype PackageNameP = PackageNameP { unPackageNameP :: PackageName }
 instance PersistField PackageNameP where
-  toPersistValue (PackageNameP pn) = PersistText $ displayC pn
+  toPersistValue (PackageNameP pn) = PersistText $ T.pack $ packageNameString pn
   fromPersistValue v = do
     str <- fromPersistValue v
     case parsePackageName str of
@@ -448,7 +452,7 @@ instance PersistFieldSql PackageNameP where
 
 newtype VersionP = VersionP Version
 instance PersistField VersionP where
-  toPersistValue (VersionP v) = PersistText $ displayC v
+  toPersistValue (VersionP v) = PersistText $ T.pack $ versionString v
   fromPersistValue v = do
     str <- fromPersistValue v
     case parseVersion str of
@@ -509,7 +513,7 @@ instance Show PackageIdentifierRevision where
 
 instance Display PackageIdentifierRevision where
   display (PackageIdentifierRevision name version cfi) =
-    displayC name <> "-" <> displayC version <> display cfi
+    fromString (packageNameString name) <> "-" <> fromString (versionString version) <> display cfi
 
 instance ToJSON PackageIdentifierRevision where
   toJSON = toJSON . utf8BuilderToText . display
@@ -648,9 +652,9 @@ instance Display PantryException where
        Just version
          | version > cabalSpecLatestVersion ->
              "\n\nThe cabal file uses the cabal specification version " <>
-             displayC version <>
+             fromString (versionString version) <>
              ", but we only support up to version " <>
-             displayC cabalSpecLatestVersion <>
+             fromString (versionString cabalSpecLatestVersion) <>
              ".\nRecommended action: upgrade your build tool (e.g., `stack upgrade`)."
        _ -> mempty)
   display (TreeWithoutCabalFile pl) = "No cabal file found for " <> display pl
@@ -662,7 +666,7 @@ instance Display PantryException where
     fromString (toFilePath fp) <>
     " does not match the package name it defines.\n" <>
     "Please rename the file to: " <>
-    displayC name <>
+    fromString (packageNameString name) <>
     ".cabal\n" <>
     "For more information, see: https://github.com/commercialhaskell/stack/issues/317"
   display (NoCabalFileFound dir) =
@@ -699,7 +703,7 @@ instance Display PantryException where
     displayShow e
   display (MismatchedPackageMetadata loc pm mtreeKey foundCabal foundIdent) =
     "Mismatched package metadata for " <> display loc <>
-    "\nFound: " <> displayC foundIdent <> " with cabal file " <>
+    "\nFound: " <> fromString (packageIdentifierString foundIdent) <> " with cabal file " <>
     display foundCabal <>
     (case mtreeKey of
        Nothing -> mempty
@@ -718,7 +722,7 @@ instance Display PantryException where
   display (WrongCabalFileName pl sfp name) =
     "Wrong cabal file name for package " <> display pl <>
     "\nCabal file is named " <> display sfp <>
-    ", but package name is " <> displayC name <>
+    ", but package name is " <> fromString (packageNameString name) <>
     "\nFor more information, see:\n  - https://github.com/commercialhaskell/stack/issues/317\n  -https://github.com/commercialhaskell/stack/issues/895"
   display (DownloadInvalidSHA256 url Mismatch {..}) =
     "Mismatched SHA256 hash from " <> display url <>
@@ -745,7 +749,8 @@ instance Display PantryException where
     "Unsupported tar filetype in archive " <> display loc <> " at file " <> fromString fp <> ": " <> displayShow x
   display (UnsupportedTarball loc e) =
     "Unsupported tarball from " <> display loc <> ": " <> display e
-  display (NoHackageCryptographicHash ident) = "Not cryptographic hash found for Hackage package " <> displayC ident
+  display (NoHackageCryptographicHash ident) =
+    "Not cryptographic hash found for Hackage package " <> fromString (packageIdentifierString ident)
   display (FailedToCloneRepo repo) = "Failed to clone repo " <> display repo
   display (TreeReferencesMissingBlob loc sfp key) =
     "The package " <> display loc <>
@@ -772,8 +777,8 @@ instance Display PantryException where
   display (MismatchedCabalFileForHackage pir Mismatch{..}) =
     "When processing cabal file for Hackage package " <> display pir <>
     ":\nMismatched package identifier." <>
-    "\nExpected: " <> displayC mismatchExpected <>
-    "\nActual:   " <> displayC mismatchActual
+    "\nExpected: " <> fromString (packageIdentifierString mismatchExpected) <>
+    "\nActual:   " <> fromString (packageIdentifierString mismatchActual)
 
 data FuzzyResults
   = FRNameNotFound ![PackageName]
@@ -786,7 +791,7 @@ displayFuzzy (FRNameNotFound names) =
     Nothing -> ""
     Just names' ->
       "\nPerhaps you meant " <>
-      orSeparated (NE.map displayC names') <>
+      orSeparated (NE.map (fromString . packageNameString) names') <>
       "?"
 displayFuzzy (FRVersionNotFound pirs) =
   "\nPossible candidates: " <>
@@ -1015,13 +1020,35 @@ parseVersionRange = Distribution.Text.simpleParse
 parseFlagName :: String -> Maybe FlagName
 parseFlagName = Distribution.Text.simpleParse
 
--- | Display Cabal types using 'Distribution.Text.Text'.
+-- | Render a package name as a 'String'.
 --
--- FIXME this should be removed and replaced with monomorphic functions for safety.
+-- @since 0.1.0.0
+packageNameString :: PackageName -> String
+packageNameString = unPackageName
+
+-- | Render a package identifier as a 'String'.
+--
+-- @since 0.1.0.0
+packageIdentifierString :: PackageIdentifier -> String
+packageIdentifierString = Distribution.Text.display
+
+-- | Render a version as a 'String'.
+--
+-- @since 0.1.0.0
+versionString :: Version -> String
+versionString = Distribution.Text.display
+
+-- | Render a flag name as a 'String'.
+--
+-- @since 0.1.0.0
+flagNameString :: FlagName -> String
+flagNameString = unFlagName
+
+-- | Render a module name as a 'String'.
 --
 -- @since 0.1.0.0
-displayC :: (IsString str, Distribution.Text.Text a) => a -> str
-displayC = fromString . Distribution.Text.display
+moduleNameString :: ModuleName -> String
+moduleNameString = Distribution.Text.display
 
 data OptionalSubdirs
   = OSSubdirs !(NonEmpty Text)
@@ -1061,8 +1088,8 @@ instance NFData PackageMetadata
 
 instance Display PackageMetadata where
   display pm = fold $ intersperse ", " $ catMaybes
-    [ (\name -> "name == " <> displayC name) <$> pmName pm
-    , (\version -> "version == " <> displayC version) <$> pmVersion pm
+    [ (\name -> "name == " <> fromString (packageNameString name)) <$> pmName pm
+    , (\version -> "version == " <> fromString (versionString version)) <$> pmVersion pm
     , (\tree -> "tree == " <> display tree) <$> pmTreeKey pm
     , (\cabal -> "cabal file == " <> display cabal) <$> pmCabal pm
     ]
@@ -1284,7 +1311,7 @@ unCabalStringMap = Map.mapKeysMonotonic unCabalString
 instance Distribution.Text.Text a => ToJSON (CabalString a) where
   toJSON = toJSON . Distribution.Text.display . unCabalString
 instance Distribution.Text.Text a => ToJSONKey (CabalString a) where
-  toJSONKey = toJSONKeyText $ displayC . unCabalString
+  toJSONKey = toJSONKeyText $ T.pack . Distribution.Text.display . unCabalString
 
 instance forall a. IsCabalString a => FromJSON (CabalString a) where
   parseJSON = withText name $ \t ->
@@ -1346,8 +1373,9 @@ data WantedCompiler
 instance NFData WantedCompiler
 instance Store WantedCompiler
 instance Display WantedCompiler where
-  display (WCGhc vghc) = "ghc-" <> displayC vghc
-  display (WCGhcjs vghcjs vghc) = "ghcjs-" <> displayC vghcjs <> "_ghc-" <> displayC vghc
+  display (WCGhc vghc) = "ghc-" <> fromString (versionString vghc)
+  display (WCGhcjs vghcjs vghc) =
+    "ghcjs-" <> fromString (versionString vghcjs) <> "_ghc-" <> fromString (versionString vghc)
 instance ToJSON WantedCompiler where
   toJSON = toJSON . utf8BuilderToText . display
 instance FromJSON WantedCompiler where
@@ -1607,25 +1635,25 @@ instance Store PackageName where
     VarSize $ \name ->
     case size of
       ConstSize x -> x
-      VarSize f -> f (displayC name :: String)
+      VarSize f -> f (packageNameString name)
   peek = peek >>= maybe (fail "Invalid package name") pure . parsePackageName
-  poke name = poke (displayC name :: String)
+  poke name = poke (packageNameString name)
 instance Store Version where
   size =
     VarSize $ \version ->
     case size of
       ConstSize x -> x
-      VarSize f -> f (displayC version :: String)
+      VarSize f -> f (versionString version)
   peek = peek >>= maybe (fail "Invalid version") pure . parseVersion
-  poke version = poke (displayC version :: String)
+  poke version = poke (versionString version)
 instance Store FlagName where
   size =
     VarSize $ \fname ->
     case size of
       ConstSize x -> x
-      VarSize f -> f (displayC fname :: String)
+      VarSize f -> f (flagNameString fname)
   peek = peek >>= maybe (fail "Invalid flag name") pure . parseFlagName
-  poke fname = poke (displayC fname :: String)
+  poke fname = poke (flagNameString fname)
 instance Store ModuleName where
   size =
     VarSize $ \mname ->