And patterns in Haskell

AndPatterns.hs

{-# LANGUAGE LambdaCase      #-}
{-# LANGUAGE PatternSynonyms #-}
{-# LANGUAGE ViewPatterns    #-}

module AndPatterns where

pattern DivBy3 :: Integral i => i
pattern DivBy3 <- ((`mod` 3) -> 0)

pattern DivBy5 :: Integral i => i
pattern DivBy5 <- ((`mod` 5) -> 0)

pattern (:&:) :: a -> a -> a
pattern (:&:) i j <- (\x -> (x,x) -> (i,j))

fizzbuzz :: Int -> String
fizzbuzz = \case
  DivBy3 :&: DivBy5 -> "fizzbuzz"
  DivBy3            -> "fizz"
  DivBy5            -> "buzz"
  i                 -> show i