Well one thing: when you work on enough code for long enough you start to forget what's/what. Static typing let's you jump in and immediately know the shape of your data at any point in the code, without having to re-trace execution manually
Yep, many projects grow to a point where it’s literally impossible for anyone to keep track of the full data model in their head. At that point, you end up needing to refer back to schemas and/or jump around the codebase constantly in order to to get anything done. This is when static types and IDE autocomplete start saving you significant time and energy.
I know what you mean. I code in ways that compensate for that problem. Actually minimizing my need to remember anything but intentions. Smalltalk rewards that style vehemently for example. And I use Smalltalk and JavaScript in that style and I don't feel any less productive or particularly vulnerable to correctness issues. While in a TypeScript project I'm working I do feel a productivity hit (not in the good sense) and I (and my teammates) keep asking ourselves "what TS is helping us with, really"? So far the only thing I can say is that TypeScript is a fantastic solution for all the problems that it creates itself.
I'm genuinely curious how you code in such a way that compensates for the problem. I'm unfamiliar with Smalltalk but very familiar with JS/Typescript.
I'm sure that if tight-knit group held strongly to certain naming conventions, then you could convey structure through the semantics. My experience though has been that anything that relies heavily on "holding strongly to convention and form" falls quickly to business speed, forgetfulness, and laziness.
As a personal example, a couple of coworkers and I were working on a codebase in JS, and there was some function that helped manipulate user objects. There were however two types of user objects, that were _very_ structurally similar, but with slight variances. Because of the similarities, people started calling user functions with one type that were meant for the other type, and it would work. Future modifications would inevitably cause failures, as unexpected parameters were being passed in.
