[ruby-core:94918] [Ruby master Feature#8970] Array.zip and Array.product

Issue #8970 has been updated by inopinatus (Joshua GOODALL).


In my private library I have a higher-order function called "fold":

    class Array
      class << self
        def fold((head, *tail), &block)
          block::(head, *tail)
        end
      end

      def fold(&block)
        self.class.fold(self, &block)
      end
    end

then...

    arrays = [["a", "b"], ["c"], ["d", "e"]]

    arrays.fold(&:product)
    #=> [["a", "c", "d"], ["a", "c", "e"], ["b", "c", "d"], ["b", "c", "e"]]



----------------------------------------
Feature #8970: Array.zip and Array.product
https://bugs.ruby-lang.org/issues/8970#change-81532

* Author: sawa (Tsuyoshi Sawada)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
=begin
Most of the time when I use `Array#zip` or `Array#product`, I feel cumbursome that I have to take out the first array and pass it as a receiver. For example, if I have

    a = [[:a, :b, :c], [:d, :e, :f], [:g, :h, :i]]

I have to do something like this:

    a.first.zip(*a.drop(1)){...}
    a.first.product(*a.drop(1)){...}

Sometimes, the receiver (i.e., the first array) has significance, but most other times, that breaks asymmetry, making the code look ugly. 

I would be happy if we had `Array.zip` and `Array.product` in addition so that we can do it like this:

    Array.zip(*a){...}
    Array.product(*a){...}

=end




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