Right -- people already use defer as a way of mapping errors and doing cleanup in an already awful way: func something() (Err error) { defer func()

Right -- people already use defer as a way of mapping errors and doing cleanup in an already awful way: func something() (Err error) { defer func() { if Err != nil { someCleanup() Err = fmt.Errorf("wrapping: %v", Err) } }() return blah() } And unlike handle you can actually give an arbitrary mapping function, while as far as I can tell you'd need to do something like handle err { return mapError(err) } Rather than the more ergonomic handle mapError Or handle func(err Error) { return mapError(err) } But whatever -- all of this is pretty useless. The main benefit of check in my mind is actually that you would be able to easily bump your test coverage -- because Go test coverage is based on lines and so the repeated use of if err != nil { return err } artificially dilutes your test coverage (you don't need to test that every error is propagated -- that's just doesn't make any sense and might not be possible if you are returning directly from os.* functions that don't even have fault-injection).