Glad to see this here. I came to know about SETL long after I had acquainted myself with (and subsequently enamored with) Python. What was quite shocking and refreshing to me was how modern this much older language felt. One just cannot miss how much SETL had influenced Python. It grounded my then Python fanboyism a bit, I realized that many of the things that I had considered novel werent that novel after all.

Wish SETL had not fallen out through the cracks in terms of popularity and mainstream usage.

Surprising, I used ISETL back in the late 90s a part of an abstract algebra course. It was quite good at demonstrating the concepts, and served as an introduction to programming/computers for a few of the pure math students. Fun to see it pop up here.

> Maps are provided as sets of pairs

Does it mean this can be a map?

{(k1, v1), (k1, v2)}

I think you have to use square brackets...

    stuff := {['k1','v1'],['k2','v2'],['k2','v3']};
    
    print (stuff('k1'));
    print (stuff{'k2'});

What I meant is that it sounds like it's possible to have two entries in a map with the same key.

Yes, they are multi-maps, and can have multiple values for the same key. In that case you have to use curly brackets to deference, and you'll get a set back with the values.