class Dry::Types::Default

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

def call_safe(input = Undefined, &block)
  if input.equal?(Undefined)
    evaluate
  else
    Undefined.default(type.call_safe(input, &block)) { evaluate }
  end
end

def call_unsafe(input = Undefined)
  if input.equal?(Undefined)
    evaluate
  else
    Undefined.default(type.call_unsafe(input)) { evaluate }
  end
end

def callable?
  false
end

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

def default?
  true
end

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

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

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