namespace Pair =

  function fst(t : ('a * 'b)) : 'a = switch(t)
    (x, _) => x

  function snd(t : ('a * 'b)) : 'b = switch(t)
    (_, y) => y

/** Map over first
 */
  function map1(f : 'a => 'c, t : ('a * 'b)) : ('c * 'b) = switch(t)
    (x, y) => (f(x), y)

/** Map over second
 */
  function map2(f : 'b => 'c, t : ('a * 'b)) : ('a * 'c) = switch(t)
    (x, y) => (x, f(y))

/** Map over both
 */
  function bimap(f : 'a => 'c, g : 'b => 'd, t : ('a * 'b)) : ('c * 'd) = switch(t)
    (x, y) => (f(x), g(y))

  function swap(t : ('a * 'b)) : ('b * 'a) = switch(t)
    (x, y) => (y, x)