{-# OPTIONS_GHC -Wwarn #-} {-# LANGUAGE CPP, ScopedTypeVariables, OverloadedStrings, Rank2Types #-} {-# LANGUAGE LambdaCase #-} ----------------------------------------------------------------------------- -- | -- Module : Haddock -- Copyright : (c) Simon Marlow 2003-2006, -- David Waern 2006-2010, -- Mateusz Kowalczyk 2014 -- License : BSD-like -- -- Maintainer : haddock@projects.haskell.org -- Stability : experimental -- Portability : portable -- -- Haddock - A Haskell Documentation Tool -- -- Program entry point and top-level code. ----------------------------------------------------------------------------- module Haddock ( haddock, haddockWithGhc, getGhcDirs, readPackagesAndProcessModules, withGhc ) where import Haddock.Backends.Xhtml import Haddock.Backends.Xhtml.Meta import Haddock.Backends.Xhtml.Themes (getThemes) import Haddock.Backends.LaTeX import Haddock.Backends.Hoogle import Haddock.Backends.Hyperlinker import Haddock.Interface import Haddock.Interface.Json import Haddock.Parser import Haddock.Types import Haddock.Version import Haddock.InterfaceFile import Haddock.Options import Haddock.Utils import Haddock.GhcUtils (modifySessionDynFlags, setOutputDir) import Control.Monad hiding (forM_) import Control.Monad.IO.Class (MonadIO(..)) import Data.Bifunctor (second) import Data.Foldable (forM_, foldl') import Data.Traversable (for) import Data.List (isPrefixOf) import Control.Exception import Data.Maybe import Data.IORef import Data.Map (Map) import Data.Version (makeVersion) import qualified Data.Map as Map import System.IO import System.Exit import System.FilePath #ifdef IN_GHC_TREE import System.Environment (getExecutablePath) #else import qualified GHC.Paths as GhcPaths import Paths_haddock_api (getDataDir) #endif import System.Directory (doesDirectoryExist, getTemporaryDirectory) import Text.ParserCombinators.ReadP (readP_to_S) import GHC hiding (verbosity) import GHC.Settings.Config import GHC.Driver.Session hiding (projectVersion, verbosity) import GHC.Utils.Outputable (defaultUserStyle, withPprStyle) import GHC.Driver.Env import GHC.Utils.Error import GHC.Unit import GHC.Utils.Panic (handleGhcException) import GHC.Data.FastString -------------------------------------------------------------------------------- -- * Exception handling -------------------------------------------------------------------------------- handleTopExceptions :: IO a -> IO a handleTopExceptions = handleNormalExceptions . handleHaddockExceptions . handleGhcExceptions -- | Either returns normally or throws an ExitCode exception; -- all other exceptions are turned into exit exceptions. handleNormalExceptions :: IO a -> IO a handleNormalExceptions inner = (inner `onException` hFlush stdout) `catches` [ Handler (\(code :: ExitCode) -> exitWith code) , Handler (\(ex :: AsyncException) -> case ex of StackOverflow -> do putStrLn "stack overflow: use -g +RTS -K to increase it" exitFailure _ -> do putStrLn ("haddock: " ++ show ex) exitFailure) , Handler (\(ex :: SomeException) -> do putStrLn ("haddock: internal error: " ++ show ex) exitFailure) ] handleHaddockExceptions :: IO a -> IO a handleHaddockExceptions inner = catches inner [Handler handler] where handler (e::HaddockException) = do putStrLn $ "haddock: " ++ show e exitFailure handleGhcExceptions :: IO a -> IO a handleGhcExceptions = -- error messages propagated as exceptions handleGhcException $ \e -> do hFlush stdout print (e :: GhcException) exitFailure ------------------------------------------------------------------------------- -- * Top level ------------------------------------------------------------------------------- -- | Run Haddock with given list of arguments. -- -- Haddock's own main function is defined in terms of this: -- -- > main = getArgs >>= haddock haddock :: [String] -> IO () haddock args = haddockWithGhc withGhc args haddockWithGhc :: (forall a. [Flag] -> Ghc a -> IO a) -> [String] -> IO () haddockWithGhc ghc args = handleTopExceptions $ do -- Parse command-line flags and handle some of them initially. -- TODO: unify all of this (and some of what's in the 'render' function), -- into one function that returns a record with a field for each option, -- or which exits with an error or help message. (flags, files) <- parseHaddockOpts args shortcutFlags flags qual <- rightOrThrowE (qualification flags) sinceQual <- rightOrThrowE (sinceQualification flags) -- inject dynamic-too into flags before we proceed flags'' <- ghc flags $ do df <- getDynFlags case lookup "GHC Dynamic" (compilerInfo df) of Just "YES" -> return $ Flag_OptGhc "-dynamic-too" : flags _ -> return flags flags' <- pure $ case optParCount flags'' of Nothing -> flags'' Just Nothing -> Flag_OptGhc "-j" : flags'' Just (Just n) -> Flag_OptGhc ("-j" ++ show n) : flags'' -- bypass the interface version check let noChecks = Flag_BypassInterfaceVersonCheck `elem` flags -- Create a temporary directory and redirect GHC output there (unless user -- requested otherwise). -- -- Output dir needs to be set before calling 'depanal' since 'depanal' uses it -- to compute output file names that are stored in the 'DynFlags' of the -- resulting 'ModSummary's. let withDir | Flag_NoTmpCompDir `elem` flags = id | otherwise = withTempOutputDir unless (Flag_NoWarnings `elem` flags) $ do hypSrcWarnings flags forM_ (warnings args) $ \warning -> do hPutStrLn stderr warning when noChecks $ hPutStrLn stderr noCheckWarning ghc flags' $ withDir $ do dflags <- getDynFlags unit_state <- hsc_units <$> getSession forM_ (optShowInterfaceFile flags) $ \path -> liftIO $ do mIfaceFile <- readInterfaceFiles freshNameCache [(("", Nothing), path)] noChecks forM_ mIfaceFile $ \(_, ifaceFile) -> do logOutput dflags $ withPprStyle defaultUserStyle (renderJson (jsonInterfaceFile ifaceFile)) if not (null files) then do (packages, ifaces, homeLinks) <- readPackagesAndProcessModules flags files -- Dump an "interface file" (.haddock file), if requested. forM_ (optDumpInterfaceFile flags) $ \path -> liftIO $ do writeInterfaceFile path InterfaceFile { ifInstalledIfaces = map toInstalledIface ifaces , ifLinkEnv = homeLinks } -- Render the interfaces. liftIO $ renderStep dflags unit_state flags sinceQual qual packages ifaces else do when (any (`elem` [Flag_Html, Flag_Hoogle, Flag_LaTeX]) flags) $ throwE "No input file(s)." -- Get packages supplied with --read-interface. packages <- liftIO $ readInterfaceFiles freshNameCache (readIfaceArgs flags) noChecks -- Render even though there are no input files (usually contents/index). liftIO $ renderStep dflags unit_state flags sinceQual qual packages [] -- | Run the GHC action using a temporary output directory withTempOutputDir :: Ghc a -> Ghc a withTempOutputDir action = do tmp <- liftIO getTemporaryDirectory x <- liftIO getProcessID let dir = tmp ".haddock-" ++ show x modifySessionDynFlags (setOutputDir dir) withTempDir dir action -- | Create warnings about potential misuse of -optghc warnings :: [String] -> [String] warnings = map format . filter (isPrefixOf "-optghc") where format arg = concat ["Warning: `", arg, "' means `-o ", drop 2 arg, "', did you mean `-", arg, "'?"] -- | Create a warning about bypassing the interface version check noCheckWarning :: String noCheckWarning = "Warning: `--bypass-interface-version-check' can cause " ++ "Haddock to crash when reading Haddock interface files." withGhc :: [Flag] -> Ghc a -> IO a withGhc flags action = do libDir <- fmap (fromMaybe (error "No GhcDir found") . snd) (getGhcDirs flags) -- Catches all GHC source errors, then prints and re-throws them. let handleSrcErrors action' = flip handleSourceError action' $ \err -> do printException err liftIO exitFailure needHieFiles = Flag_HyperlinkedSource `elem` flags withGhc' libDir needHieFiles (ghcFlags flags) (\_ -> handleSrcErrors action) readPackagesAndProcessModules :: [Flag] -> [String] -> Ghc ([(DocPaths, InterfaceFile)], [Interface], LinkEnv) readPackagesAndProcessModules flags files = do -- Get packages supplied with --read-interface. let noChecks = Flag_BypassInterfaceVersonCheck `elem` flags packages <- readInterfaceFiles nameCacheFromGhc (readIfaceArgs flags) noChecks -- Create the interfaces -- this is the core part of Haddock. let ifaceFiles = map snd packages (ifaces, homeLinks) <- processModules (verbosity flags) files flags ifaceFiles return (packages, ifaces, homeLinks) renderStep :: DynFlags -> UnitState -> [Flag] -> SinceQual -> QualOption -> [(DocPaths, InterfaceFile)] -> [Interface] -> IO () renderStep dflags unit_state flags sinceQual nameQual pkgs interfaces = do updateHTMLXRefs pkgs let ifaceFiles = map snd pkgs installedIfaces = concatMap ifInstalledIfaces ifaceFiles extSrcMap = Map.fromList $ do ((_, Just path), ifile) <- pkgs iface <- ifInstalledIfaces ifile return (instMod iface, path) render dflags unit_state flags sinceQual nameQual interfaces installedIfaces extSrcMap -- | Render the interfaces with whatever backend is specified in the flags. render :: DynFlags -> UnitState -> [Flag] -> SinceQual -> QualOption -> [Interface] -> [InstalledInterface] -> Map Module FilePath -> IO () render dflags unit_state flags sinceQual qual ifaces installedIfaces extSrcMap = do let title = fromMaybe "" (optTitle flags) unicode = Flag_UseUnicode `elem` flags pretty = Flag_PrettyHtml `elem` flags opt_wiki_urls = wikiUrls flags opt_contents_url = optContentsUrl flags opt_index_url = optIndexUrl flags odir = outputDir flags opt_latex_style = optLaTeXStyle flags opt_source_css = optSourceCssFile flags opt_mathjax = optMathjax flags dflags' | unicode = gopt_set dflags Opt_PrintUnicodeSyntax | otherwise = dflags visibleIfaces = [ i | i <- ifaces, OptHide `notElem` ifaceOptions i ] -- /All/ visible interfaces including external package modules. allIfaces = map toInstalledIface ifaces ++ installedIfaces allVisibleIfaces = [ i | i <- allIfaces, OptHide `notElem` instOptions i ] pkgMod = fmap ifaceMod (listToMaybe ifaces) pkgKey = fmap moduleUnit pkgMod pkgStr = fmap unitString pkgKey pkgNameVer = modulePackageInfo unit_state flags pkgMod pkgName = fmap (unpackFS . (\(PackageName n) -> n)) (fst pkgNameVer) sincePkg = case sinceQual of External -> pkgName Always -> Nothing (srcBase, srcModule, srcEntity, srcLEntity) = sourceUrls flags srcModule' | Flag_HyperlinkedSource `elem` flags = Just hypSrcModuleUrlFormat | otherwise = srcModule srcMap = Map.union (Map.map SrcExternal extSrcMap) (Map.fromList [ (ifaceMod iface, SrcLocal) | iface <- ifaces ]) pkgSrcMap = Map.mapKeys moduleUnit extSrcMap pkgSrcMap' | Flag_HyperlinkedSource `elem` flags , Just k <- pkgKey = Map.insert k hypSrcModuleNameUrlFormat pkgSrcMap | Just srcNameUrl <- srcEntity , Just k <- pkgKey = Map.insert k srcNameUrl pkgSrcMap | otherwise = pkgSrcMap -- TODO: Get these from the interface files as with srcMap pkgSrcLMap' | Flag_HyperlinkedSource `elem` flags , Just k <- pkgKey = Map.singleton k hypSrcModuleLineUrlFormat | Just path <- srcLEntity , Just k <- pkgKey = Map.singleton k path | otherwise = Map.empty sourceUrls' = (srcBase, srcModule', pkgSrcMap', pkgSrcLMap') installedMap :: Map Module InstalledInterface installedMap = Map.fromList [ (unwire (instMod iface), iface) | iface <- installedIfaces ] -- The user gives use base-4.9.0.0, but the InstalledInterface -- records the *wired in* identity base. So untranslate it -- so that we can service the request. unwire :: Module -> Module unwire m = m { moduleUnit = unwireUnit unit_state (moduleUnit m) } reexportedIfaces <- concat `fmap` (for (reexportFlags flags) $ \mod_str -> do let warn = hPutStrLn stderr . ("Warning: " ++) case readP_to_S parseHoleyModule mod_str of [(m, "")] | Just iface <- Map.lookup m installedMap -> return [iface] | otherwise -> warn ("Cannot find reexported module '" ++ mod_str ++ "'") >> return [] _ -> warn ("Cannot parse reexported module flag '" ++ mod_str ++ "'") >> return []) libDir <- getHaddockLibDir flags prologue <- getPrologue dflags' flags themes <- getThemes libDir flags >>= either bye return let withQuickjump = Flag_QuickJumpIndex `elem` flags when (Flag_GenIndex `elem` flags) $ do withTiming dflags' "ppHtmlIndex" (const ()) $ do _ <- {-# SCC ppHtmlIndex #-} ppHtmlIndex odir title pkgStr themes opt_mathjax opt_contents_url sourceUrls' opt_wiki_urls allVisibleIfaces pretty return () copyHtmlBits odir libDir themes withQuickjump when (Flag_GenContents `elem` flags) $ do withTiming dflags' "ppHtmlContents" (const ()) $ do _ <- {-# SCC ppHtmlContents #-} ppHtmlContents unit_state odir title pkgStr themes opt_mathjax opt_index_url sourceUrls' opt_wiki_urls allVisibleIfaces True prologue pretty sincePkg (makeContentsQual qual) return () copyHtmlBits odir libDir themes withQuickjump when (Flag_Html `elem` flags) $ do withTiming dflags' "ppHtml" (const ()) $ do _ <- {-# SCC ppHtml #-} ppHtml unit_state title pkgStr visibleIfaces reexportedIfaces odir prologue themes opt_mathjax sourceUrls' opt_wiki_urls opt_contents_url opt_index_url unicode sincePkg qual pretty withQuickjump return () copyHtmlBits odir libDir themes withQuickjump writeHaddockMeta odir withQuickjump -- TODO: we throw away Meta for both Hoogle and LaTeX right now, -- might want to fix that if/when these two get some work on them when (Flag_Hoogle `elem` flags) $ do case pkgNameVer of (Just (PackageName pkgNameFS), mpkgVer) -> let pkgNameStr | unpackFS pkgNameFS == "main" && title /= [] = title | otherwise = unpackFS pkgNameFS pkgVer = fromMaybe (makeVersion []) mpkgVer in ppHoogle dflags' unit_state pkgNameStr pkgVer title (fmap _doc prologue) visibleIfaces odir _ -> putStrLn . unlines $ [ "haddock: Unable to find a package providing module " ++ maybe "" (moduleNameString . moduleName) pkgMod ++ ", skipping Hoogle." , "" , " Perhaps try specifying the desired package explicitly" ++ " using the --package-name" , " and --package-version arguments." ] when (Flag_LaTeX `elem` flags) $ do withTiming dflags' "ppLatex" (const ()) $ do _ <- {-# SCC ppLatex #-} ppLaTeX title pkgStr visibleIfaces odir (fmap _doc prologue) opt_latex_style libDir return () when (Flag_HyperlinkedSource `elem` flags && not (null ifaces)) $ do withTiming dflags' "ppHyperlinkedSource" (const ()) $ do _ <- {-# SCC ppHyperlinkedSource #-} ppHyperlinkedSource (verbosity flags) odir libDir opt_source_css pretty srcMap ifaces return () ------------------------------------------------------------------------------- -- * Reading and dumping interface files ------------------------------------------------------------------------------- readInterfaceFiles :: MonadIO m => NameCacheAccessor m -> [(DocPaths, FilePath)] -> Bool -> m [(DocPaths, InterfaceFile)] readInterfaceFiles name_cache_accessor pairs bypass_version_check = do catMaybes `liftM` mapM ({-# SCC readInterfaceFile #-} tryReadIface) pairs where -- try to read an interface, warn if we can't tryReadIface (paths, file) = readInterfaceFile name_cache_accessor file bypass_version_check >>= \case Left err -> liftIO $ do putStrLn ("Warning: Cannot read " ++ file ++ ":") putStrLn (" " ++ err) putStrLn "Skipping this interface." return Nothing Right f -> return $ Just (paths, f) ------------------------------------------------------------------------------- -- * Creating a GHC session ------------------------------------------------------------------------------- -- | Start a GHC session with the -haddock flag set. Also turn off -- compilation and linking. Then run the given 'Ghc' action. withGhc' :: String -> Bool -> [String] -> (DynFlags -> Ghc a) -> IO a withGhc' libDir needHieFiles flags ghcActs = runGhc (Just libDir) $ do dynflags' <- parseGhcFlags =<< getSessionDynFlags -- We disable pattern match warnings because than can be very -- expensive to check let dynflags'' = unsetPatternMatchWarnings $ updOptLevel 0 dynflags' -- ignore the following return-value, which is a list of packages -- that may need to be re-linked: Haddock doesn't do any -- dynamic or static linking at all! _ <- setSessionDynFlags dynflags'' ghcActs dynflags'' where -- ignore sublists of flags that start with "+RTS" and end in "-RTS" -- -- See https://github.com/haskell/haddock/issues/666 filterRtsFlags :: [String] -> [String] filterRtsFlags flgs = foldr go (const []) flgs True where go "-RTS" func _ = func True go "+RTS" func _ = func False go _ func False = func False go arg func True = arg : func True parseGhcFlags :: MonadIO m => DynFlags -> m DynFlags parseGhcFlags dynflags = do -- TODO: handle warnings? let extra_opts | needHieFiles = [Opt_WriteHie, Opt_Haddock] | otherwise = [Opt_Haddock] dynflags' = (foldl' gopt_set dynflags extra_opts) { backend = NoBackend , ghcMode = CompManager , ghcLink = NoLink } flags' = filterRtsFlags flags (dynflags'', rest, _) <- parseDynamicFlags dynflags' (map noLoc flags') if not (null rest) then throwE ("Couldn't parse GHC options: " ++ unwords flags') else return dynflags'' unsetPatternMatchWarnings :: DynFlags -> DynFlags unsetPatternMatchWarnings dflags = foldl' wopt_unset dflags pattern_match_warnings where pattern_match_warnings = [ Opt_WarnIncompletePatterns , Opt_WarnIncompleteUniPatterns , Opt_WarnIncompletePatternsRecUpd , Opt_WarnOverlappingPatterns ] ------------------------------------------------------------------------------- -- * Misc ------------------------------------------------------------------------------- getHaddockLibDir :: [Flag] -> IO FilePath getHaddockLibDir flags = case [str | Flag_Lib str <- flags] of [] -> do #ifdef IN_GHC_TREE -- When in the GHC tree, we should be able to locate the "lib" folder -- based on the location of the current executable. base_dir <- getBaseDir -- Provided by GHC let res_dirs = [ d | Just d <- [base_dir] ] ++ #else -- When Haddock was installed by @cabal@, the resources (which are listed -- under @data-files@ in the Cabal file) will have been copied to a -- special directory. data_dir <- getDataDir -- Provided by Cabal let res_dirs = [ data_dir ] ++ #endif -- When Haddock is built locally (eg. regular @cabal new-build@), the data -- directory does not exist and we are probably invoking from either -- @./haddock-api@ or @./@ [ "resources" , "haddock-api/resources" ] res_dir <- check res_dirs case res_dir of Just p -> return p _ -> die "Haddock's resource directory does not exist!\n" fs -> return (last fs) where -- Pick the first path that corresponds to a directory that exists check :: [FilePath] -> IO (Maybe FilePath) check [] = pure Nothing check (path : other_paths) = do exists <- doesDirectoryExist path if exists then pure (Just path) else check other_paths -- | Find the @lib@ directory for GHC and the path to @ghc@ getGhcDirs :: [Flag] -> IO (Maybe FilePath, Maybe FilePath) getGhcDirs flags = do #ifdef IN_GHC_TREE base_dir <- getBaseDir let ghc_path = Nothing #else let base_dir = Just GhcPaths.libdir ghc_path = Just GhcPaths.ghc #endif -- If the user explicitly specifies a lib dir, use that let ghc_dir = case [ dir | Flag_GhcLibDir dir <- flags ] of [] -> base_dir xs -> Just (last xs) pure (ghc_path, ghc_dir) #ifdef IN_GHC_TREE -- | See 'getBaseDir' in "SysTools.BaseDir" getBaseDir :: IO (Maybe FilePath) getBaseDir = do -- Getting executable path can fail. Turn that into 'Nothing' exec_path_opt <- catch (Just <$> getExecutablePath) (\(_ :: SomeException) -> pure Nothing) -- Check that the path we are about to return actually exists case exec_path_opt of Nothing -> pure Nothing Just exec_path -> do let base_dir = takeDirectory (takeDirectory exec_path) "lib" exists <- doesDirectoryExist base_dir pure (if exists then Just base_dir else Nothing) #endif shortcutFlags :: [Flag] -> IO () shortcutFlags flags = do usage <- getUsage when (Flag_Help `elem` flags) (bye usage) when (Flag_Version `elem` flags) byeVersion when (Flag_InterfaceVersion `elem` flags) (bye (show binaryInterfaceVersion ++ "\n")) when (Flag_CompatibleInterfaceVersions `elem` flags) (bye (unwords (map show binaryInterfaceVersionCompatibility) ++ "\n")) when (Flag_GhcVersion `elem` flags) (bye (cProjectVersion ++ "\n")) when (Flag_PrintGhcPath `elem` flags) $ do path <- fmap fst (getGhcDirs flags) bye $ fromMaybe "not available" path ++ "\n" when (Flag_PrintGhcLibDir `elem` flags) $ do dir <- fmap snd (getGhcDirs flags) bye $ fromMaybe "not available" dir ++ "\n" when (Flag_UseUnicode `elem` flags && Flag_Html `notElem` flags) $ throwE "Unicode can only be enabled for HTML output." when ((Flag_GenIndex `elem` flags || Flag_GenContents `elem` flags) && Flag_Html `elem` flags) $ throwE "-h/--html cannot be used with --gen-index or --gen-contents" when ((Flag_GenIndex `elem` flags || Flag_GenContents `elem` flags) && Flag_Hoogle `elem` flags) $ throwE "--hoogle cannot be used with --gen-index or --gen-contents" when ((Flag_GenIndex `elem` flags || Flag_GenContents `elem` flags) && Flag_LaTeX `elem` flags) $ throwE "--latex cannot be used with --gen-index or --gen-contents" where byeVersion = bye $ "Haddock version " ++ projectVersion ++ ", (c) Simon Marlow 2006\n" ++ "Ported to use the GHC API by David Waern 2006-2008\n" -- | Generate some warnings about potential misuse of @--hyperlinked-source@. hypSrcWarnings :: [Flag] -> IO () hypSrcWarnings flags = do when (hypSrc && any isSourceUrlFlag flags) $ hPutStrLn stderr $ concat [ "Warning: " , "--source-* options are ignored when " , "--hyperlinked-source is enabled." ] when (not hypSrc && any isSourceCssFlag flags) $ hPutStrLn stderr $ concat [ "Warning: " , "source CSS file is specified but " , "--hyperlinked-source is disabled." ] where hypSrc = Flag_HyperlinkedSource `elem` flags isSourceUrlFlag (Flag_SourceBaseURL _) = True isSourceUrlFlag (Flag_SourceModuleURL _) = True isSourceUrlFlag (Flag_SourceEntityURL _) = True isSourceUrlFlag (Flag_SourceLEntityURL _) = True isSourceUrlFlag _ = False isSourceCssFlag (Flag_SourceCss _) = True isSourceCssFlag _ = False updateHTMLXRefs :: [(DocPaths, InterfaceFile)] -> IO () updateHTMLXRefs packages = do writeIORef html_xrefs_ref (Map.fromList mapping) writeIORef html_xrefs_ref' (Map.fromList mapping') where mapping = [ (instMod iface, html) | ((html, _), ifaces) <- packages , iface <- ifInstalledIfaces ifaces ] mapping' = [ (moduleName m, html) | (m, html) <- mapping ] getPrologue :: DynFlags -> [Flag] -> IO (Maybe (MDoc RdrName)) getPrologue dflags flags = case [filename | Flag_Prologue filename <- flags ] of [] -> return Nothing [filename] -> do h <- openFile filename ReadMode hSetEncoding h utf8 str <- hGetContents h -- semi-closes the handle return . Just $! second (fmap rdrName) $ parseParas dflags Nothing str _ -> throwE "multiple -p/--prologue options" rightOrThrowE :: Either String b -> IO b rightOrThrowE (Left msg) = throwE msg rightOrThrowE (Right x) = pure x