Should I define interfaces in Duck Typed languages?

Question

I\'m just about to write my first application in a duck typed language (Groovy).

If I was to write the same application in a static typed language then I would need to d

Answer 1

Defining an interface is a kind of in-code documentation. With an interface you declare explicitly what you expect from the class to satisfy your needs.

PS: groovy is not my language, so I actually don't know whether it's possible to define interfaces there at all.