IO
: ∀(A: *) *
= λA
  $(self: (IO A))
  ∀(P: ∀(x: (IO A)) *)
  ∀(print: 
    ∀(text: String) ∀(then: ∀(x: Unit) (IO A))
    (P (IO.print A text then))
  )
  ∀(load: 
    ∀(file: String) ∀(then: ∀(x: String) (IO A))
    (P (IO.load A file then))
  )
  ∀(save: 
    ∀(file: String)
    ∀(data: String)
    ∀(then: ∀(x: Unit) (IO A))
    (P (IO.save A file data then))
  )
  ∀(done: ∀(term: A) (P (IO.done A term)))
  (P self)