If you do make a slight tweak somewhere, the compiler will tell you there’s something broken in obscure place X that you would find out at runtime say with Ruby or Python.
THATS the winning formula. I’ve written so many tests for Python ensuring a function’s arguments are validated rather than the core logic/process of it.
Not so fast. For some problems it's great, for other ones it's not.
Have you tried writing numeric or machine leaning core in Haskell? You'll notice that the type system just doesn't help you enforce correctness. Have you tried writing low level IO? The logic is too complex to capture on types, if you try to use them you'll have a huge problem.
Rust's got a very Haskell-like type system, but it's a systems programming language. People are literally writing kernels in it. I think this is a pure-functional-is-a-bad-way-to-do-real-time-I/O thing, not a typing thing.
That said, I don't think it's impossible to type IO. https://lexi-lambda.github.io/blog/2020/01/19/no-dynamic-typ... isn't the same problem, but it's related.
If you try to verify the kind of state machines that low level I/O normally use with Haskell-like types, you will gain a huge amount of complexity and probably end with more bugs than without.
Let's say you're writing a /dev/console driver for an RS-232 connection. Trying to represent "ring indicator", "parity failure", "invalid UTF-8 sequence", "keyboard interrupt", "hup" and "buffer full" at the same level in the type system will fail abysmally, but that's not a sensible way of doing it.
I could definitely implement this while leveraging the power of Rust's type system – Haskell would be a stretch, but only because it's side-effect free and I/O is pretty much all side-effects.
If you're doing React + Typescript give Reasonml which is a syntax sugar on top of Ocaml that compiles using bucklescript a go. Ocaml has the fastest compiler out there.
Meanwhile the plugins and IDE integrations for Reason/Ocaml and F# are ready to go from the start and work pretty well.