I have been using F# for 5 years and have never once needed to use “null” anywhere in my code - if I were to interact with a C# library I think null-handling is

I have been using F# for 5 years and have never once needed to use “null” anywhere in my code - if I were to interact with a C# library I think null-handling is an acceptable price to pay for the interop (similar to weirdness with OCaml/Haskell and C FFI). F# makes that particular separation of concerns very clean and easy to handle. Idiomatic F# is safe against null reference exceptions. I think you’re needling a small wart in F# due to the .NET requirement, it’s hardly enough to say that F#’s type system is overall bad.