Array#disjointed

class Array(T)
	# Returns true if the two arrays share no common elements.
	def disjointed?(other : Array(U)) forall U
		(self & other).size == 0
	end
end

arr1 = [1 ,2 ,3, 4]
arr2 = [3, 4, 5, 6]
arr3 = [5, 6, 7, 8]

puts arr1.disjointed?(arr2)
puts arr2.disjointed?(arr3)
puts arr1.disjointed?(arr3)