APL was not originally a programming language (pardon the pun) but as a notation for array mathematics. https://en.wikipedia.org/wiki/APL_(programming_language

APL was not originally a programming language (pardon the pun) but as a notation for array mathematics. https://en.wikipedia.org/wiki/APL_(programming_language) https://en.wikipedia.org/wiki/APL_(programming_language) "A mathematical notation for manipulating arrays was developed by Kenneth E. Iverson, starting in 1957 at Harvard University. In 1960, he began work for IBM where he developed this notation with Adin Falkoff and published it in his book A Programming Language in 1962." It didn't become an actual (usable) programming language until 1963.