procedure pi (q, r, t, k, n, l)
  first := "yes"
  repeat { # infinite loop
    if (4*q+r-t < n*t) then {
      suspend n
      if (\first) := &null then suspend "."
      # compute and update variables for next cycle
      nr := 10*(r-n*t)
      n := ((10*(3*q+r)) / t) - 10*n
      q *:= 10
      r := nr
    } else {
      # compute and update variables for next cycle
      nr := (2*q+r)*l
      nn := (q*(7*k+2)+r*l) / (t*l)
      q *:= k
      t *:= l
      l +:= 2
      k +:= 1
      n := nn
      r := nr
    }
  }
end

procedure main ()
  every (writes (pi (1,0,1,1,3,3)))
end