Simple calculator in ruby

calculator.rb

operation = "1 + 1 + 20 - 3 "
Kernel.eval operation
# 19

raw_ops = operation.split /(\+|-)/
ops = raw_ops.map { |raw_op| Integer(raw_op, exception: false) || raw_op }
# [1, "+", 1, "+", 20, "-", 3]

while ops.size > 1
  operator = ops.delete_at(1)
  operand = ops.delete_at(1)
  ops[0] = ops[0].send(operator, operand)
end

ops.first
# 19