This exercise shouldn't have been that challenging, but it stumped me. Here's my woeful journey with the path through it so that I can review my approach when I get stuck on the next exercise.
Found in the Purescript Book, exercise 2:
(Medium) Write a function
foldMto determine all possible totals that could be made using a set of coins. The coins will be specified as an array which contains the value of each coin. Your function should have the following result: