(match (* t *)
  leaf
  (match (* r *)
    (let:tree:cf leaf (w{mono} node))
    (match (* rr *)
      (let:tree:cf (w node) (let:tree:cf leaf (w{mono} node)))
      (w{mono l2xy} (let:tree:cf
        (tick app) (* splay_max rr *)
        (match
          leaf
          (let:tree:cf node (let:tree:cf node (w{mono} node)))
        )
      ))
    )
  )
)