So yeah, exception as part of explicit function signature is a vast improvement, I completely agree

Hmm, I'm not sure if you are being sarcastic. In my reply I didn't meant encoding Exceptions into Type system. Is this a type and you probably meant "Error Types as part of" instead "exception as part of"?

Honestly I don't know how Exceptions as part of type system would even look like. Because each function call in a chain would need to have all information from previous function call, otherwise that information gets lost to the next caller. The problem is the hierarchy of function and method calls. Somewhere some objects and functions can be edited to Throw a new Exception, that is not handled through the entire chain. And for the higher function caller, there is 0% way of knowing that (through code, besides documentation off course).