lets
` <*>
  + pure (GHC.Show.show)
  ` <|>
    + <*>
    | + <*>
    | | + pure (\x_0 -> \x_1 -> x_0)
    | | ` pure ('a')
    | ` satisfy
    ` <*>
      + <*>
      | + pure (\x_0 -> \x_1 -> x_0)
      | ` pure ('b')
      ` satisfy