> Many codebases are littered with them [null checks] and, > as a result they [codebases] are often very hard to understand. I wager they're referring to

> Many codebases are littered with them [null checks] and, > as a result they [codebases] are often very hard to understand. I wager they're referring to null checks complicating the codebase (introducing uncertainty into method signatures and argument values down the chain). And that's what creates a ripe environment for such bugs and vulnerabilities that you mention. Anyways, my big a-ha moment in programming was when I started thinking in terms of data-structures and mapping functions/transformations across them. (map update-phone (filter ... users))