On the other hand, with Rust and Haskell you absolutely need type constructors to be easily discoverable. If open gives me an Fd, but the library function accep

On the other hand, with Rust and Haskell you absolutely need type constructors to be easily discoverable. If open gives me an Fd, but the library function accepts a Stream, I shouldn't need to spend hours wading through sparse documentation to find how to convert between the two. Something like Hoogle becomes a necessity if you want your type system to replace the need for documentation.