[stefanchrobot]

Why not both? I want the language to provide an iterable/enumerable interface with the usual generic workhorses (map, reduce, etc.) and allow me to implement that interface as a free function for any type. If I'm authoring a type, I'll add specialized functions as needed.

[aardvark179]

Ruby manages to do this. The default implementations of all the methods you want are on the enumerable module, so if you implement the “each” method you get everything, including the ability to get an enumerator object that you can pass round and use for anything else you want.