Enumerators-ruby.rb

a = [1, 3, "cat"]
b = {
  dog: "ben",
  cat: "tom"
}
enum_a = a.to_enum #untuk
enum_b = b.to_enum

enum_a1 = a.each

#puts "Enumator is #{enum_a1.next[2]}"
# puts enum_a1.next
# puts enum_a1.next
#
# puts enum_a.next
# p enum_b.next
# puts enum_a.next
# p enum_b.next

short_enum = (1..100).to_enum
long_enum = ('a'..'z').to_enum
# loop do
#   puts "#{short_enum.next} - #{long_enum.next}"
# end

# result = []
# index = 1
# [ 'a', 'b', 'c', 'd' ].each_with_index {
#   |item, index| result << [item, index]
#   }
#   p result

enum = "cat as".enum_for(:each_char)
#p enum.to_a

# result = []
# "cat".each_char.each_with_index {
#   |item, index| result << [item, index]
#   }
#   p result
#

  # enum_in_three = (1..12).enum_for(:each_slice, 3)
  # p enum_in_three.to_a

triangular_numbers = Enumerator.new do |yielder|
  number = 0
  count = 1
  loop do
    number +=count
    count +=1
    yielder.yield number
  end
end
#
# 5.times {
#   print triangular_numbers.next, ","
# }
# puts
puts "Result 5 from triangular_numbers is #{triangular_numbers.first(5)}"

def infinite_select(enum, &block)
  Enumerator.new do |yielder|
    enum.each do |value|
      yielder.yield(value) if block.call(value)
    end
  end
end
p infinite_select(triangular_numbers) {|val| val % 10 == 0}.first(5)