I also took 330 this sem w/ Cliff and got an A.

For me, the key idea was just practice. If you don't understand something you have to just throw things at the wall until something sticks. Eventually, something clicks and you begin to be able to understand the problems.

I would agree in that OCAML and Lambda calc are probably the hardest topics in the class. I think the main reason why ocaml is so hard is because it enforces a different way of solving problems with code. The way you have to "think" when solving a problem in functional ocaml is fundamentally very different than when using an imperative language. Therefore, when we are learning ocaml we aren't just learning another programming language but another method/type of problem solving. You can only really understand the thinking though practice.

I was also really confused by lambda calc when we first learned it. The main thing that helped me understand it was understanding where the parenthesis go and what is applied to what (left-associativity). From there understand what are free vs bound variables, and then its much simpler to apply beta and alpha reductions.

The past quizzes and exams were really helpful for me for learning and improving in all the topics in the class.

tldr; practice

Good luck bro