IO.run
: ∀(A: *)
  ∀(x: (IO A))
  (IO A)
= λA λx
  let P     = λx(IO A)
  let print = λtext λthen (HVM.print (IO A) text (IO.run A (then Unit.one)))
  let load  = λfile λthen (HVM.load (IO A) file λs(IO.run A (then s)))
  let save  = λfile λdata λthen (HVM.save (IO A) file data (IO.run A (then Unit.one)))
  let done  = λterm (IO.done A term)
  (~x P print load save done)