one : unitone : unitone_CASE : unit -> α -> αone_DEF⊢ () = @x. T
one_TY_DEF⊢ ∃rep. TYPE_DEFINITION (λb. b) rep
one_case_def⊢ ∀u x. one_CASE u x = x
⊢ (∃f. P f) ⇔ ∃f. P (λx u. f x)
⊢ (∀x. P x) ⇔ P ()
⊢ (∀uf. P uf) ⇔ ∀a. P (λu. a)
⊢ ∀v. v = ()
⊢ ∀e. ∃!fn. fn () = e
⊢ ∀f g. f = g
⊢ ∀x. one_CASE () x = x
⊢ ∀P. P () ⇒ ∀x. P x
⊢ ∀e. ∃fn. fn () = e