X.Prompt: X constraint for historyCompletion[P]

This is needed because the cache directory is now a part of XConf, which
is calculated once on startup and hence any recalculation would be
fragile.

Some internal functions that are not exposed (like writeHistory) were
also changed to accept that directory as an argument.

XMonad/Actions/Search.hs

@@ -363,18 +363,16 @@ namedEngine name (SearchEngine _ site) = searchEngineF name site
    Prompt's result, passes it to a given searchEngine and opens it in a given
    browser. -}
 promptSearchBrowser :: XPConfig -> Browser -> SearchEngine -> X ()
-promptSearchBrowser config browser (SearchEngine name site) =
-    mkXPrompt (Search name) config (historyCompletionP ("Search [" `isPrefixOf`)) $ search browser site
+promptSearchBrowser config browser (SearchEngine name site) = do
+    hc <- historyCompletionP ("Search [" `isPrefixOf`)
+    mkXPrompt (Search name) config hc $ search browser site
 
 {- | Like 'promptSearchBrowser', but only suggest previous searches for the
    given 'SearchEngine' in the prompt. -}
 promptSearchBrowser' :: XPConfig -> Browser -> SearchEngine -> X ()
-promptSearchBrowser' config browser (SearchEngine name site) =
-    mkXPrompt
-        (Search name)
-        config
-        (historyCompletionP (searchName `isPrefixOf`))
-        $ search browser site
+promptSearchBrowser' config browser (SearchEngine name site) = do
+    hc <- historyCompletionP (searchName `isPrefixOf`)
+    mkXPrompt (Search name) config hc $ search browser site
   where
     searchName = showXPrompt (Search name)
 

XMonad/Prompt.hs

@@ -543,7 +543,8 @@ mkXPromptImplementation historyKey conf om = do
   XConf { display = d, theRoot = rw } <- ask
   s <- gets $ screenRect . W.screenDetail . W.current . windowset
   numlock <- gets X.numberlockMask
-  hist <- io readHistory
+  cachedir <- getXMonadCacheDir
+  hist <- io $ readHistory cachedir
   fs <- initXMF (font conf)
   st' <- io $
     bracket
@@ -562,7 +563,7 @@ mkXPromptImplementation historyKey conf om = do
   releaseXMF fs
   when (successful st') $ do
     let prune = take (historySize conf)
-    io $ writeHistory $
+    io $ writeHistory cachedir $
       M.insertWith
       (\xs ys -> prune . historyFilter conf $ xs ++ ys)
       historyKey
@@ -1560,21 +1561,21 @@ type History = M.Map String [String]
 emptyHistory :: History
 emptyHistory = M.empty
 
-getHistoryFile :: IO FilePath
-getHistoryFile = fmap (++ "/prompt-history") getXMonadCacheDir
+getHistoryFile :: FilePath -> FilePath
+getHistoryFile cachedir = cachedir ++ "/prompt-history"
 
-readHistory :: IO History
-readHistory = readHist `E.catch` \(SomeException _) -> return emptyHistory
+readHistory :: FilePath -> IO History
+readHistory cachedir = readHist `E.catch` \(SomeException _) -> return emptyHistory
  where
     readHist = do
-        path <- getHistoryFile
+        let path = getHistoryFile cachedir
         xs <- bracket (openFile path ReadMode) hClose hGetLine
         readIO xs
 
-writeHistory :: History -> IO ()
-writeHistory hist = do
-  path <- getHistoryFile
-  let filtered = M.filter (not . null) hist
+writeHistory :: FilePath -> History -> IO ()
+writeHistory cachedir hist = do
+  let path = getHistoryFile cachedir
+      filtered = M.filter (not . null) hist
   writeFile path (show filtered) `E.catch` \(SomeException e) ->
                           hPutStrLn stderr ("error writing history: "++show e)
   setFileMode path mode
@@ -1667,14 +1668,17 @@ breakAtSpace s
 -- | 'historyCompletion' provides a canned completion function much like
 --   'getShellCompl'; you pass it to mkXPrompt, and it will make completions work
 --   from the query history stored in the XMonad cache directory.
-historyCompletion :: ComplFunction
+historyCompletion :: X ComplFunction
 historyCompletion = historyCompletionP (const True)
 
 -- | Like 'historyCompletion' but only uses history data from Prompts whose
 -- name satisfies the given predicate.
-historyCompletionP :: (String -> Bool) -> ComplFunction
-historyCompletionP p x = fmap (toComplList . M.filterWithKey (const . p)) readHistory
-    where toComplList = deleteConsecutive . filter (isInfixOf x) . M.foldr (++) []
+historyCompletionP :: (String -> Bool) -> X ComplFunction
+historyCompletionP p = do
+    cd <- getXMonadCacheDir
+    pure $ \x ->
+        let toComplList = deleteConsecutive . filter (isInfixOf x) . M.foldr (++) []
+         in toComplList . M.filterWithKey (const . p) <$> readHistory cd
 
 -- | Sort a list and remove duplicates. Like 'deleteAllDuplicates', but trades off
 --   laziness and stability for efficiency.