{-# LANGUAGE RecursiveDo #-}

bar = do { foo; bar }

baz =
  mdo bar a
      a <- foo
      b <- bar
        1 2 3
      return (a + b)

baz = do
  a <- foo
  let b = a + 2
      c = b + 3
  bar c
  let d = c + 2
  return d

quux = something $ do
  foo
  case x of
    1 -> 10
    2 -> 20
  bar
  if something
  then x
  else y
  baz