Comment by cubefox

> That needs a qualifier: it can make easy problems tough if you're not familiar with how to solve them in a functional context.

All problems are easy if you are familiar with how to solve them. Unfortunately it's part of the problem to find out how to solve them, and that can be unusually hard in case of functional programming. Like solving something with recursion instead of loops + states. There is a reason cookbooks use loops not recursion.