While compile failures were easy to fix for syb, X11 and xmonad, here's a more mysterious encounter with xmonad-contrib. The module in question is http://code.haskell.org/XMonadContrib/XMonad/Layout/MultiToggle.hs and the rest of this mail is the error: XMonad/Layout/MultiToggle.hs:194:30: Could not deduce (Typeable a) from the context (Typeable a, Show ts, HList ts a, LayoutClass l a) arising from a use of `fromMessage' Possible fix: add (Typeable a) to the context of the instance declaration In a stmt of a pattern guard for an equation for `handleMessage': Just (Toggle t) <- fromMessage m In an equation for `handleMessage': handleMessage mt m | Just (Toggle t) <- fromMessage m, i@(Just _) <- find (transformers mt) t = case currLayout mt of { EL l det -> do { l' <- fromMaybe l `fmap` handleMessage l (SomeMessage ReleaseResources); .... } where cur = (i == currIndex mt) } | otherwise = case currLayout mt of { EL l det -> fmap (fmap (\ x -> mt {currLayout = EL x det})) $ handleMessage l m } In the instance declaration for `LayoutClass (MultiToggle ts l) a' XMonad/Layout/MultiToggle.hs:195:25: Could not deduce (HList ts a) from the context (Typeable a, Show ts, HList ts a, LayoutClass l a, Transformer t a) arising from a use of `find' Possible fix: add (HList ts a) to the context of the data constructor `Toggle' or the instance declaration In a stmt of a pattern guard for an equation for `handleMessage': i@(Just _) <- find (transformers mt) t In a stmt of a pattern guard for an equation for `handleMessage': Just (Toggle t) <- fromMessage m In an equation for `handleMessage': handleMessage mt m | Just (Toggle t) <- fromMessage m, i@(Just _) <- find (transformers mt) t = case currLayout mt of { EL l det -> do { l' <- fromMaybe l `fmap` handleMessage l (SomeMessage ReleaseResources); .... } where cur = (i == currIndex mt) } | otherwise = case currLayout mt of { EL l det -> fmap (fmap (\ x -> mt {currLayout = EL x det})) $ handleMessage l m }