• Top = \E α.α

  • AnyPair = \E α\E β.α×β

  • (3,4):\E α.α - does not provide sufficient structure!

  • (3,4):\E α.α×α
  
  • \E α.α×( α→ Int )

  • x : \E α. α×( α→ Int )

slide: Existential types -- examples