[C++, Java](http://www.geeksforgeeks.org/g-fact-75/), Dlang, [C#](https://stackoverflow.com/questions/20705643/method-overloading-with-different-return-type) etc don't allow this either... But IMSHO (in my humble stupid option) it would still be a good idea.
I thought Nim's philosophy was to not make the programmer jump through hoops (ex. namespace prefixes) to make ambiguity impossible, but to have the compiler figure it out if possible, or have an error if ambiguity actually exists. Outright disabling overloading by return type is an inconsistency with this philosophy. Overloading by return type would only work when assigning to something that has a declared type, otherwise (if using discard or expecting type inference) you'd get an error.
