module Kernel
  def to_json(*a)
    to_s.to_json(*a)
  end
end

class String
  def to_json(*a)
    inspect
  end
end

class Array
  def to_json(*a)
    parts = collect { |o| o.to_json(*a) }
    "[#{parts.join ', '}]"
  end
end

class Hash
  def to_json(*a)
    parts = []
    each { |k, v| parts << "#{k.to_json(*a)}: #{v.to_json(*a)}" }
    "{#{parts.join ', '}}"
  end
end

class Numeric
  def to_json(*a)
    to_s
  end
end

class TrueClass
  def to_json(*a)
    "true"
  end
end

class FalseClass
  def to_json(*a)
    "false"
  end
end

class NilClass
  def to_json(*a)
    "null"
  end
end