Make Hamming conform to official definition

[exercism]

Make Hamming conform to official definition

[soniakeys]

Addressed with PR #107

[kytrinyx]

I'm reopening this per the discussion here: exercism/exercism#1910

Summary: The definition of "not defined" means anything could happen.

[soniakeys]

Undefined behavior is not idiomatic Go. I'm against removing the error return. Actually I think this is an excellent problem to introduce the error result. The problem is fairly simple, and the error condition is both intuitively clear and trivial to detect. (Queen-attack uses the error return and is currently ahead of Hamming in config.json, but I'm not sure it should stay there. I expected most people would find Queen-attack a harder problem.) Anyway Hamming is currenly 17th in config.json. The error return is such an funcamental part of Go that I would actually be happy with introducing it return earlier!

I know I tried to make this thing happen with introducing error handling with the Binary/Octal/Hex sequence but that turned out a little strange. I think there are now four problems that require error handling before Binary. In Binary, the concept was to put the error return in the API but not check the value in the tests. We could do the same here for Hamming but really this is kind of strange thing to do. Go doesn't allow variable assignment unless the variable is used. Requiring a return value that is never checked is close to the same thing.

With the current README, we could add a comment to the test file explaining to return an error for unequal lengths but I think the API and tests are okay the way they are.

[kytrinyx]

Undefined behavior is not idiomatic Go.

Yeah, you're right. I think that here the language trumps Wikipedia, and that creating a contract makes sense. I'm going to close again.

I do think that hamming would make sense earlier in the series.