class Plumb::InterfaceClass

def ==(other)
  other.is_a?(self.class) && other.method_names == method_names
end

def _inspect = "Interface[#{method_names.join(', ')}]"

def call(result)
  obj = result.value
  missing_methods = @method_names.reject { |m| obj.respond_to?(m) }
  return result.invalid(errors: "missing methods: #{missing_methods.join(', ')}") if missing_methods.any?
  result
end

def initialize(method_names = [])
  @method_names = method_names
  freeze
end

def of(*args)
  case args
  in Array => symbols if symbols.all? { |s| s.is_a?(::Symbol) }
    self.class.new(symbols)
  else
    raise ::ArgumentError, "unexpected value to Types::Interface#of #{args.inspect}"
  end
end