[[a b] ->
  [[b a gt?]   [a]
   [otherwise] [b]] opt
] [max] def

[[dup length 1 lt?] [[max] doin] while ...] [maximum] def

[[a b] ->
  [[b a lt?]   [a]
   [otherwise] [b]] opt
] [min] def

[[dup length 1 lt?] [[min] doin] while ...] [minimum] def