For one, Swift avoids what Tony Hoare calls his Billion Dollar Mistake (conflating optionality and reference types). Because Tony Hoare introduced null referen

For one, Swift avoids what Tony Hoare calls his Billion Dollar Mistake (conflating optionality and reference types). Because Tony Hoare introduced null references to Algol W, most Algol-derived and Algol-inspired statically typed languages since have made all pointers/references nullable. Some, like Java, have bolted on Lint-like null checkers an afterthought (see @Nullable, @NotNull) outside of the official compiler. It's really nice to have the compiler not allow callers to pass null to functions where passing null wouldn't make sense, isn't useful, or the programmer was just too lazy to implement null checks. More than half of the functions I write have inputs where null wouldn't have an obvious meaning. Objective-C's treatment of nil receivers is particularly handy for programming in the small and particularly bad for programming in the large. Sending a message to nil (similar to calling a method on null in many other languages) does nothing other than returning 0 cast to the type of variable you're storing the return value in. Chugging along accidentally accumulating nulls in many cases is worse than segfaulting and giving a nice stack trace. Certainly in the realm of automated trading software, segfaulting when hitting a programming error is preferable to most other failure modes. Of course, failing to compile is often (though not always) the best failure mode.