lazysort.jl

# Lazy quicksort.
# Can be used to take only the first k elements of the sorted array,
# And will do this 'efficiently'
lazysort{T}(lst::Vector{T}) =
@task begin
	if     length(lst) == 0   # is sorting trivial?
	elseif length(lst) == 1
		produce(lst[1])
	else
		# take pivot element
		pivot = lst[rand(1:length(lst))]

		# partition array
		lt, gt = T[], T[]
		for i in lst
			push!(i <= pivot ? lt : gt, i)
		end

		# sort subdivided
		for i in lazysort(lt); produce(i); end
		for i in lazysort(gt); produce(i); end
	end
end