I went to a small university with only 8 CS professors. One of them was the author of J's array parallelization and he taught our Intro to Functional Languages

I went to a small university with only 8 CS professors. One of them was the author of J's array parallelization and he taught our Intro to Functional Languages course. That class was fourth in the undergrad sequence, coming after C, C++ and Java so it was quite a shock to, well, everyone. He took us from finding the average of a list all the way through to implementing a CMS in J (our department web server still runs on J because he's since retired and no one else knows how to maintain it). This was easily the hardest class in the entire department. Students who sailed through everything else would struggle to pass. It's a fascinating language but not an easy one to grasp.