. package:xmonad-contrib

(.) :: (b -> c) -> (a -> b) -> a -> c
xmonad-contrib XMonad.Config.Prime
Right to left function composition. 
(f . g) x = f (g x)

f . id = f = id . f

Examples

>>> map ((*2) . length) [[], [0, 1, 2], [0]]
[0,6,2]

>>> foldr (.) id [(+1), (*3), (^3)] 2
25

>>> let (...) = (.).(.) in ((*2)...(+)) 5 10
30
(.|.) :: Bits a => a -> a -> a
xmonad-contrib XMonad.Config.Prime
Bitwise "or"
(.:) :: (a -> b) -> (c -> d -> a) -> c -> d -> b
xmonad-contrib XMonad.Prelude
Multivariable composition. 
f .: g ≡ (f .) . g ≡ \c d -> f (g c d)
(.|) :: Logger -> Logger -> Logger
xmonad-contrib XMonad.Util.Loggers
An infix operator for logDefault, which can be more convenient to combine multiple loggers. 
logTitle .| logWhenActive 0 (logConst "*") .| logConst "There's nothing here"
(=.) :: UpdateableClass s x y => s c -> (x -> y) -> Arr c c
xmonad-contrib XMonad.Config.Prime
This lets you apply a function to an attribute (i.e. read, modify, write).