> This isn't specific to Rust or Typescript. You can do this in basically any language.

This just isn't true.

In any dynamic language you would not get these guarantees at compile time. You'd get random failures at runtime. That's not safety of any kind.

Also, part of the goal of languages like Haskell is that they help you think about your code before it runs. All of that is lost.

> Imagine you have to distinguish between unescaped and escaped strings for security purposes

That would be a nightmare in many languages. You'd have to rewrite large parts of the code to be compatible with one or both. And in many languages you'd have to duplicate your code entirely.

In other languages, the result would so ugly, you would never want to touch that code. Imagine doing this with say, templates in C++.

>There's a performance cost to this

There is no performance cost in Haskell! This is entirely undone by the compiler.

Also, because the compiler understands what's going on at a much higher level, you can do things like deriving code. You can say that your classified strings behave like your regular strings in most contexts, like say, they're the same for the purpose of printing but not for the purpose of equality, in one line.