We've known about algorithms for millennia, but we've only been writing c- puter programs for a few decades. A big di?erence between the Euclidean or Eratosthenes age and ours is that since the middle of the twentieth century, we express the algorithms we conceive using formal languages: programming languages. Computer scientists are not the only ones who use formal languages. - tometrists, for example, prescribe eyeglasses using very technical expressions,...