stew/unison-pi

An example unison program to estimate pi

.> display trunk.README

  
  
  This is an example Unison project which estimates Π by picking points randomly inside a 2 unit square
  and counts how many fall inside a unit circle. Over time, the ratio of points inside and outside of
  the circle should converge on Π.
  
  trunk.estimatePi rounds =
    loop : Nat -> Nat -> Nat -> Float
    loop left hit total =
      if Nat.eq left 0 then
        use Float * /
        use Nat toFloat
        [: After all the rounds have run, the ration of hits to total should be ¼Π :]
        4.0 * (toFloat hit / toFloat total)
      else
        hit' =
          use Nat +
          hit + (if testPoint !nextPoint then 1 else 0)
        loop (Nat.decrement left) hit' (Nat.increment total)
    mersenne.provide int.next defaultSeed '(loop rounds 0 0)