inopinatus/array_fold.rb

Created September 12, 2019 04:12

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Array#fold

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array_fold.rb

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

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

Author

inopinatus commented Sep 12, 2019

Usage:

arrays = [["a", "b"], ["c"], ["d", "e"]]
hashes = [{"a" => 1}, {"b" => 2, "c" => 3}, {"d" => 4, "e" => 5}]

arrays.fold(&:product) # => [["a", "c", "d"], ["a", "c", "e"], ["b", "c", "d"], ["b", "c", "e"]]
arrays.fold(&:zip)     # => [["a", "c", "d"], ["b", nil, "e"]]
arrays.fold(&:union)   # => ["a", "b", "c", "d", "e"]
hashes.fold(&:merge)   # => {"a"=>1, "b"=>2, "c"=>3, "d"=>4, "e"=>5}

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