(match
  (w{mono} leaf)
  (match
    (let:tree:cf (w{mono} leaf) (w{l2xy} node))
    (w{l2xy}
      (tick
        (w{l2xy mono}
          (let:tree:cf
            (w{l2xy}
              (tick
                (w{l2xy mono}
                  (let:tree:cf
                    (w{l2xy} (tick (w{l2xy} (shift app))))
                    (let:tree:cf
                      (w{mono} node)
                      (let:tree:cf (w{mono} node) (shift app))
                    )
                  )
                )
              )
            )
            (shift app)
          )
        )
      )
    )
  )
)