Whenever I'm bored, I try to understand flatMap

would be nice to have a HackerRank style set of problem sets for that wouldn't it?

What is your current limit of understanding it, i.e. what are you currently struggling with?

I generally understand the construction.. (you know, the canonical example of splitting a string of words by spaces, which returns a collection, which is then flattened). But there seem to be so many ways to use it differently.. resolving futures, spark dataframes, scala collections, all have their idiosyncratic ways of processing the results The dsls of the transformations are the most confusing for me. When I’m bored at work like I am now, I think of all of the ways that flatmap gets used and I try to refresh my memory on how it’s used. For some reason, it’s harder for me to grok than any other idiom.