It feels more natural to you because of familiarity. However, if you've learned Iverson Bracket notation in math (https://en.wikipedia.org/wiki/Iverson_bracket

It feels more natural to you because of familiarity. However, if you've learned Iverson Bracket notation in math (https://en.wikipedia.org/wiki/Iverson_bracket https://en.wikipedia.org/wiki/Iverson_bracket) then the APL approach will probably feel more natural, because it's a more direct expression of the mathematical foundations. Of course, the actual APL version is by far the most natural once you're familiar with the core ideas: +/ages>17