class Dry::Types::Default

def self.[](value)
  if value.respond_to?(:call)
    Callable
  else
    self
  end
end

def __new__(type)
  self.class.new(type, value, options)
end

def call(input = Undefined)
  if input.equal?(Undefined)
    evaluate
  else
    output = type[input]
    output.nil? ? evaluate : output
  end
end

def constrained(*args)
  type.constrained(*args).default(value)
end

def default?
  true
end

def initialize(type, value, **options)
  super
  @value = value
end

def try(input)
  success(call(input))
end

def valid?(value = Undefined)
  value.equal?(Undefined) || super
end