ENH use optparse for xmonad

bin/xmonad.hs

@@ -16,6 +16,7 @@ import Data.Text.IO (hPutStrLn)
 import Graphics.X11.Types
 import Graphics.X11.Xlib.Atom
 import Graphics.X11.Xlib.Extras
+import Options.Applicative hiding (action)
 import RIO
 import RIO.Directory
 import RIO.List
@@ -26,7 +27,6 @@ import System.Process
   ( getPid
   , getProcessExitCode
   )
-import UnliftIO.Environment
 import XMonad
 import XMonad.Actions.CopyWindow
 import XMonad.Actions.CycleWS
@@ -66,15 +66,38 @@ import XMonad.Util.NamedActions
 import XMonad.Util.WorkspaceCompare
 
 main :: IO ()
-main = getArgs >>= parse
+main = parse >>= xio
 
-parse :: [String] -> IO ()
-parse [] = run
-parse ["--deps"] = withCache printDeps
--- parse ["--test"] = void $ withCache . evalConf =<< connectDBusX
-parse _ = usage
+parse :: IO XOpts
+parse = execParser opts
+  where
+    parseOpts = parseDeps <|> parseTest <|> pure XRun
+    opts =
+      info (parseOpts <**> helper) $
+        fullDesc <> header "xmonad: the best window manager ever"
 
-run :: IO ()
+data XOpts = XDeps | XTest | XRun
+
+parseDeps :: Parser XOpts
+parseDeps =
+  flag'
+    XDeps
+    (long "deps" <> short 'd' <> help "print dependencies")
+
+parseTest :: Parser XOpts
+parseTest =
+  flag'
+    XTest
+    (long "test" <> short 't' <> help "test dependencies without running")
+
+xio :: XOpts -> IO ()
+xio o = withCache $
+  case o of
+    XDeps -> printDeps
+    XTest -> undefined
+    XRun -> run
+
+run :: FIO ()
 run = do
   -- These first two commands are only significant when xmonad is restarted.
   -- The 'launch' function below this will turn off buffering (so flushes are
@@ -89,7 +112,6 @@ run = do
   -- signal handlers to carry over to the top.
   uninstallSignalHandlers
   hSetBuffering stdout LineBuffering
-  withCache $ do
   withDBusX_ $ \db -> do
     let fs = features $ dbSysClient db
     startDBusInterfaces db fs
@@ -237,15 +259,6 @@ allFeatures db = withRunInIO $ \runIO -> do
   where
     ts = ThreadState {tsChildPIDs = [], tsXmobar = Nothing}
 
-usage :: IO ()
-usage =
-  putStrLn $
-    intercalate
-      "\n"
-      [ "xmonad: run greatest window manager"
-      , "xmonad --deps: print dependencies"
-      ]
-
 --------------------------------------------------------------------------------
 -- Concurrency configuration
 

package.yaml

@@ -35,6 +35,7 @@ dependencies:
   - typed-process >= 0.2.8.0
   - network >= 3.1.2.7
   - unliftio >= 0.2.21.0
+  - optparse-applicative >= 0.16.1.0
 
 library:
   source-dirs: lib/