Methods tap and itself in Crystal (for blogpost http://veelenga.com/tap-and-itself-methods-in-crystal/)

tap_and_itself.cr

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p 10.itself   # 10
p "1".itself  # "1"
p :sym.itself # :sym
p true.itself # true

p nil.itself                                 # nil
p [1, 2].itself                              # [1, 2]
p ({"1" => "2"} of String => String).itself  # {"1" => "2"}
p /1/.itself                                 # /1/

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p [1,2,4,1,2,2,3].group_by {|x| x}  # {1 => [1, 1], 2 => [2, 2, 2], 4 => [4], 3 => [3]}
p [1,2,4,1,2,2,3].group_by &.itself # {1 => [1, 1], 2 => [2, 2, 2], 4 => [4], 3 => [3]}

################################################################################
class Team
  def initialize
    @players = [] of String
  end

  def <<(player)
    @players << player
  end

  def any?
    @players.each {|player| return true if yield player}
    false
  end

  def any?
    any? &.itself
  end
end

team = Team.new.tap do |t|
  t << "Player1"
  t << "Player2"
  t << "Player3"
end

p team.any?                          # true
p team.any? {|player| player =~ /2/} # true
p team.any? {|player| player =~ /4/} # false