calc3.mirah

import java.util.HashMap

interface IOperator do
  def run(x:int, y:int)
    returns int
  end 
end

class Operators
  macro def add_op(name, &op)
    quote {
      @ops ||= HashMap.new
      @ops[`name`] = `op.body`
      
      def `name`
        IOperator(@ops[`name`])
      end
    }
  end
  
  add_op :add { |x, y| x + y }
  add_op :sub { |x, y| x - y }
end

def calculate(op:IOperator)
  op.run(4, 20)
end

op = Operators.new


puts calculate op.add

puts calculate op.sub