[IceDane]

It's not about "knowing" anything. It's about admitting that humans are fallible meat computers that can't hold invariants in their head across thousands or millions of lines of code and possibly an exponential number of interactions. It's using the technology we are capable of building to help us because it's the obvious thing to do. The notion of dynamic typing as an attractive programming model hinges entirely on the hypothesis that it lets you somehow express things that you need or want to be able to express that static typing prevents you from doing, and that is demonstrably false. The `assoc` example above is a perfect example.

[wellpast]

> that can't hold invariants in their head across thousands or millions of lines of code and possibly an exponential number of interactions.

There’s your problem. And static typing won’t save you either.

The skill is not that, it’s the ability to compose and evolve systems such that you don’t have to hold so much state in your head.

(Btw that property can hold for a million LOC codebase.)