The three hard things in #cs are:
1. Naming things
2. Cache invalidation
3. Off-by one errors
With #fp:
1. The functions' type signatures reflect all that they do, so you don't have to worry so much about names.
2. Cache invalidation is handled centrally in the runtime.
3. Higher-order recursive patterns provide a way for you to do your job without using indexes, so off with off-by-one errors.