I do have some experience, playing with an iOS app for several months, through various versions of the language (3.x, 4.x). But this was as a hobby. I liked Opt

I do have some experience, playing with an iOS app for several months, through various versions of the language (3.x, 4.x). But this was as a hobby. I liked Optionals when I learned about them, and less as I started using them. I found that libraries sometimes changed return types, e.g. T to T? (or vice versa). The feature struck me as having some drawbacks similar to Java checked exceptions: the rigor required ran counter to clean and easy to understand code. Did I just not get the design of the feature? Perhaps, but I did find it very difficult to avoid tweaking code with ? and !. I have no problem with var vs. let. I like that distinction. And I do understand that let is used only sparingly in expressions. But that's what bugs me about it, it is so limited. It is not an "orthogonal" feature, (usable in any expression). An expression is ideally functional (no side effects). Let definitely does have a side effect, declaring and binding an identifier. I find it awkward to mix the two ideas. This may be many years of mental baggage, from C, C++, and Java, but it is there, and I think that the introduction of such a major side-effect into the world of expressions is a genuinely bad idea. GC vs. reference counting: GC really does allow you to forget about memory management. Until you start running into problems requiring GC tuning. But then, the fixes tend to leave the code alone completely. With reference counting, tuning requires more intrusion into code. Yes, this is subjective. Just explaining my reasoning.