How do I translate a python generator function into ruby?

Question

I was wondering how to translate this bit of Python code into Ruby:

from __future__ import generators

def xcombinations(items, n):
    if n==0: yield []
    else:
        for i in xrange(len(items)):
            for cc in xcombinations(items[:i]+items[i+1:],n-1):
                yield [items[i]]+cc

-- my attempt at request:

def xcombinations(items, n)
    Fiber.new do
        if n == 0
            Fiber.yield []
        else
            for i in 0...items.length
                xcombinations(items[0...i]+items[i+1..-1],n-1).resume.each do |cc|
                    Fiber.yield [items[i]] << cc
                end
            end
        end
    end
end

Answer 1

I'm not sure there is a general way to translate from python to ruby but at least your example, it can be translated by using Enumerator Class as follows.

def xcombinations(items, n)
    Enumerator.new do |y|
        if n == 0 then
            y << []
        else
            for i in 0...items.length
                xcombinations(items[0...i]+items[i+1..-1],n-1).each do |cc|
                    y << [items[i]]+cc
                end
            end
        end
    end
end