Fortran 4, I was talking Fortran I. The three way if was in the language because the IBM 7094 had a single instruction that did a three way test and branch. It executed the next instriction if the predicate was<0, skipped one instriction if the predicate=0, and skipped two instructions if the predicate was>0.

Yes APL was also one of my favorites but I always knew it as Iverson Notation (Ken Iverson of IBM was the originator). Iverson notation, which was popularized as APL, was designed to be able to emulate a machine for software testing before the machine was built. In fact IBM published in one of the issues of the IBM System Journal a complete emulation of system 360 written in Iverson Notation.

APL programs were unique in that the commentary to explain the program was generally much longer than the program.