This is where list comprehensions came from! Like we have in modern Python, Haskell and more. SETL was the first language to use comprehensions in its core syntax.
Doing Advent of Code 2025 in SETL this year.
isetl was what we used for my discrete math course 20 years ago or so. I remember other students complaining about having to learn it. "when are we going to use this language".
Same and I hated it, tbh (but my experience was like 30 years ago). My prof insisted all work be done in SETL and did a terrible job of actually introducing us to the language, yet we had to submit our work as SETL code. Like, yay set theory, but I learned more implementing my homework in C and SmallTalk.
Another good example of how languages were already progressing during the 1960's.