Should we add for "APL history interest" that Perlis's delightful Introduction to computer science (1972, 1975 Harper & Row) features APL besides Algol60 as one of the two programming languages for exposing programming ?
APL is first introduced in Chapter 3 about Languages from p195 until p226. p237-38 gives a summary presentation of APL along other prominent programming languages at that time (COBOL, FORTRAN, BASIC, Algo60, Algol68, PL/I, SNOBOL, LISP).
A first list of APL exercises is given from p256-260.
In Chapter 4 about Data structures, Perlis used APL to demonstrate STRINGS, TREES structures. Applications of trees in APL are two persons board game such as Tic-Tac-Toe and generations of Huffman code.
Chapter 5 features a more advanced program using APL that I have not yet read.
I do not know how many Introduction to computer science textbooks have used APL as one of the programming languages to expose programming. This is one is still a good read for people with a keen interest in history of computer science and APL.