dice.lua

local fun = require 'fun' ()

local function avg(...)
	local sum, count = 0, 0
	for i=1,select('#', ...) do
		count = count + 1
		sum = sum + select(i, ...)
	end
	return sum / count
end

function dice(sides, number)
	if number > 0 then
		return math.random(sides), dice(sides, number-1)
	end
end

duplicate(20, 20) -- An iterator that yields two values
:take(10)
:map(dice) -- calls dice(20, 20), returning 20 integers
:map(avg) -- averages all 20 integers
:each(print)