A Programming Language is the book title. The language it describes came to be known as "APL" [0], but the author didn't explicitly name it that way in the book

A Programming Language is the book title. The language it describes came to be known as "APL" [0], but the author didn't explicitly name it that way in the book. The language "A" was created to replace APL. [0] https://en.wikipedia.org/wiki/APL_(programming_language) https://en.wikipedia.org/wiki/APL_(programming_language)