Use deepseq instead of parallel

XMonad/Actions/GroupNavigation.hs

@@ -1,3 +1,4 @@
+{-# language DeriveGeneric, DeriveAnyClass #-}
 ----------------------------------------------------------------------
 -- |
 -- Module      : XMonad.Actions.GroupNavigation
@@ -34,13 +35,14 @@ module XMonad.Actions.GroupNavigation ( -- * Usage
 
 import Control.Monad.Reader
 import Control.Monad.State
-import Control.Seq (using, seqFoldable, rseq)
+import Control.DeepSeq
 import Data.Map ((!))
 import qualified Data.Map as Map
 import Data.Sequence (Seq, ViewL (EmptyL, (:<)), viewl, (<|), (><), (|>))
 import qualified Data.Sequence as Seq
 import qualified Data.Set as Set
 import Graphics.X11.Types
+import GHC.Generics
 import Prelude hiding (concatMap, drop, elem, filter, null, reverse)
 import XMonad.Core
 import XMonad.ManageHook
@@ -157,7 +159,7 @@ orderedWorkspaceList ss wsids = rotateTo isCurWS wspcs'
 -- The state extension that holds the history information
 data HistoryDB = HistoryDB (Maybe Window) -- currently focused window
                            (Seq Window)   -- previously focused windows
-               deriving (Read, Show)
+               deriving (Read, Show, Generic, NFData)
 
 instance ExtensionClass HistoryDB where
 
@@ -168,11 +170,8 @@ instance ExtensionClass HistoryDB where
 -- focus history of all windows as the WindowSet changes.
 historyHook :: X ()
 historyHook = do
-  db <- XS.get
-  db'@(HistoryDB cur del) <- updateHistory db
-  let del' = del `using` seqFoldable rseq
-      cur' = cur `using` seqFoldable rseq
-  cur' `seq` del' `seq` XS.put db'
+  db' <- XS.get >>= updateHistory
+  db' `deepseq` XS.put db'
 
 -- Updates the history in response to a WindowSet change
 updateHistory :: HistoryDB -> X HistoryDB

XMonad/Hooks/WorkspaceHistory.hs

@@ -28,9 +28,9 @@ module XMonad.Hooks.WorkspaceHistory (
   , workspaceHistoryModify
   ) where
 
-import Control.Seq (using, seqFoldable, seqTuple2, rseq)
-import           Control.Applicative
-import           Prelude
+import Control.Applicative
+import Control.DeepSeq
+import Prelude
 import XMonad
 import XMonad.StackSet hiding (delete, filter, new)
 import XMonad.Prelude (delete, find, foldl', groupBy, nub, sortBy)
@@ -65,6 +65,13 @@ newtype WorkspaceHistory = WorkspaceHistory
                                          -- reverse-chronological order.
   } deriving (Read, Show)
 
+-- @ScreenId@ is not an instance of NFData, but is a newtype on @Int@. @seq@
+-- is enough for forcing it. This requires us to provide an instance.
+instance NFData WorkspaceHistory where
+  rnf (WorkspaceHistory hist) =
+    let go = liftRnf2 rwhnf rwhnf
+    in liftRnf go hist
+
 instance ExtensionClass WorkspaceHistory where
     initialValue = WorkspaceHistory []
     extensionType = PersistentExtension
@@ -79,14 +86,9 @@ workspaceHistoryHook = workspaceHistoryHookExclude []
 workspaceHistoryHookExclude :: [WorkspaceId] -> X ()
 workspaceHistoryHookExclude ws = do
   s <- gets windowset
-  let update' = forceHistory . updateLastActiveOnEachScreenExclude ws s
+  let update' = force . updateLastActiveOnEachScreenExclude ws s
   XS.modify' update'
 
-forceHistory :: WorkspaceHistory -> WorkspaceHistory
-forceHistory (WorkspaceHistory l) =
-  let l' = l `using` seqFoldable (seqTuple2 rseq rseq)
-  in l' `seq` WorkspaceHistory l'
-
 workspaceHistoryWithScreen :: X [(ScreenId, WorkspaceId)]
 workspaceHistoryWithScreen = XS.gets history
 

XMonad/Util/ExtensibleState.hs

@@ -94,7 +94,7 @@ modify f = put . f =<< get
 -- | Like @modify@ but the result value is applied strictly in respect to
 -- the monadic environment.
 modify' :: (ExtensionClass a, XLike m) => (a -> a) -> m ()
-modify' f = (\a -> let res = f a in res `seq` put res) =<< get
+modify' f = (put $!) . f =<< get
 
 -- | Add a value to the extensible state field. A previously stored value with the same
 -- type will be overwritten. (More precisely: A value whose string representation of its type

xmonad-contrib.cabal

@@ -62,7 +62,7 @@ library
                    X11 >= 1.10 && < 1.11,
                    xmonad >= 0.16.99999 && < 0.18,
                    utf8-string,
-                   parallel
+                   deepseq
     default-language: Haskell2010
 
     cpp-options:   -DXMONAD_CONTRIB_VERSION_MAJOR=0
@@ -449,7 +449,7 @@ test-suite tests
                , process
                , unix
                , utf8-string
-               , parallel
+               , deepseq
                , xmonad >= 0.16.9999 && < 0.18
   cpp-options: -DTESTING
   ghc-options: -Wall -Wno-unused-do-bind