With checked exceptions, if today my function can only throw a FileException, then tomorrow I cannot start throwing a URLException without breaking any callers

With checked exceptions, if today my function can only throw a FileException, then tomorrow I cannot start throwing a URLException without breaking any callers depending on my function having only one possible exception type. The lead architect of C# cited this problem as one of his reasons for not adding checked exception to that language. https://www.artima.com/intv/handcuffs.html#part2 https://www.artima.com/intv/handcuffs.html#part2 The solution to the problem with to have errors be dynamically typed (a trait in Rust, an interface in Go, etc.) and insist that callers be ready for an unknown error type to bubble up.