I remember SETL, and it made a huge impression on me -- just the idea of sets as a primitive datatype. I remember one lecture on using SETL to specify language optimizations, which were set-oriented.
Also, that experience primed me for appreciating the relational model, and relational algebra, and I went on to specialize in DBMSs.
I took one of his classes as an undergraduate at NYU, but used SNOBOL, SETL, and some other early languages as part of a young scholars high school program at NYU in the early 80s.