foo x = [a | a <- x]

bar x y = [(a, b) | a <- x, even a, b <- y, a != b]

barbaz x y z w =
  [ (a, b, c, d) -- Foo
  | a <-
      x, -- Bar
    b <- y, -- Baz
    any even [a, b],
    c <-
      z
        * z ^ 2, -- Bar baz
    d <-
      w
        + w, -- Baz bar
    all
      even
      [ a,
        b,
        c,
        d
      ]
  ]

a = do
  d <-
    [ x + 1
    | x <- b
    ]

  [ c
    | c <- d
    ]

trans =
  [ x
  | x <- xs,
    then
      reverse,
    then
      reverse
  ]