[0] https://github.com/ghc-proposals/ghc-proposals/issues/527

  (+) <$> getx <*> gety

    await x + y

  (+) <$> getx <*> gety

* summing two reads in a Transaction,

* summing two parsed numbers in a Parser,

* summing two Nullable values into one Nullable value,

* producing a Validated<T> by validating two of its parts which require validation,

* and on and on.

It's even the cartesian product when run on lists:

  let suits = ["♠", "♥", "♦", "♣"]
  let nums  = concat [["A"], map show [2..10], ["J","Q","K"]]
  let cards = (++) <$> nums <*> suits

  putStrLn (unwords (take 15 cards))
  A♠ A♥ A♦ A♣ 2♠ 2♥ 2♦ 2♣ 3♠ 3♥ 3♦ 3♣ 4♠ 4♥ 4♦

Also, it looks like you can just do it with ! in Haskell: https://hackage.haskell.org/package/monadic-bang

Yes, although it's slightly clumsy.

    example = do
      let suits = ["♠", "♥", "♦", "♣"]
      let nums  = concat [["A"], map show [2..10], ["J","Q","K"]]
      let cards = do pure (!nums ++ !suits)
      putStrLn (unwords (take 15 cards))

    ghci> example 
    A♠ A♥ A♦ A♣ 2♠ 2♥ 2♦ 2♣ 3♠ 3♥ 3♦ 3♣ 4♠ 4♥ 4♦