[matteotom]

At least for Python (since I'm more familiar with Python code and the Python ecosystem): progressive typing lets you incrementally add typing to an existing Python codebase. So you can have at least some of the benefits of typing for new or updated code without needing to re-write in a new language.

[ReflectedImage]

Gradual typing is the worse of both worlds.

You get the complexity and slower development times of using statically typed languages along with the bad performance of using dynamically typed languages.

[ck45]

Is this based on your experience or is it just an assumption? I only have anecdotes, but it does not reflect your claims, rather the exact opposite. A lot of the boilerplate code doesn’t need to be type annotated, but annotating the main business logic doesn’t take more time and is not more complicated, but instead type annotations help write code that is more clear, more obvious, and it adds some kind of documentation.

[jaapz]

Have you actually used this in a real codebase? Because it is the opposite of my experience in gradually adding types to a large python codebase. There's no extra complexity or slower development. It's not like you need to suddenly move to a different coding paradigm with FactoryBeanFactoryBeans... You just keep writing python like you did, but add types here and there to help clarify things and make your LSP (like ty) work better.

If anything, it speeds up development. Plus it helps give more confidence in the correctness of your code.

[rurban]

Nonsense. You get the simplification and faster development times of knowing some variable types statically, plus the performance improvements for the compiler which can move the type checks from runtime to compile-time. Plus all the new optimization possibilities.

Common Lisp showed you the way. But almost none looked at it. Only PHP did.