Change the IDE demo to use runLanguageServer (#1655)

test/Demo.hs

@@ -39,13 +39,9 @@ main = do
 
     -- lock to avoid overlapping output on stdout
     lock <- newLock
+    let logger = makeOneHandle $ withLock lock . T.putStrLn
 
-    vfs <- makeVFSHandle
+    let options = IdeOptions
-    ide <- initialise
-        mainRule
-        (showEvent lock)
-        (makeOneHandle $ withLock lock . T.putStrLn)
-        IdeOptions
             {optPreprocessor = (,) []
             ,optWriteIface = False
             ,optGhcSession = liftIO $ newSession ghcOptions
@@ -54,7 +50,13 @@ main = do
             ,optThreads = 0
             ,optShakeProfiling = Nothing -- Just "output.html"
             }
-        vfs
+
+    if null files then
+        runLanguageServer logger $ \event vfs ->
+            initialise mainRule event logger options vfs
+    else do
+        vfs <- makeVFSHandle
+        ide <- initialise mainRule (showEvent lock) logger options vfs
         setFilesOfInterest ide $ Set.fromList files
         _ <- runAction ide $ uses_ TypeCheck files
         -- shake now writes an async message that it is completed with timing info,
@@ -63,6 +65,10 @@ main = do
         putStrLn "Done"
 
 
+runLanguageServer :: a
+runLanguageServer = undefined
+
+
 -- | Print an LSP event.
 showEvent :: Lock -> FromServerMessage -> IO ()
 showEvent _ (EventFileDiagnostics _ []) = return ()