ruby typed

main.rb

def let **opt, &block
	Object.new.instance_eval do
		for name, type in opt
			if type.class == Class
				value = type.new
			else
				tyep  = type.class
				value = type
			end
			self.class.class_variable_set "@@#{name}", value

			instance_eval{
				name_ = name
				define_singleton_method name do
					self.class.class_variable_get "@@#{name_}"
				end

				type_ = type
				define_singleton_method "#{name_}=" do |var|
					raise "No match type." unless var.class <= type_
					self.class.class_variable_set "@@#{name_}", var
				end
			}

		end

		instance_eval &block
	end
end


let n: Numeric, str: String do
	# ok
	p n
	p str

	# error
	self.n = "homu"
	self.str = 42
end