It started as notation and grew into a language. The language retained the notation and so we get the special symbols. https://en.wikipedia.org/wiki/APL_(progr

It started as notation and grew into a language. The language retained the notation and so we get the special symbols. https://en.wikipedia.org/wiki/APL_(programming_language)#History https://en.wikipedia.org/wiki/APL_(programming_language)#His...