Design patterns are patterns which can be used for designs. All patterns can be used for designs; "design pattern" as a phrase merely signals that the pattern was described in a certain book.

Functions are too simple and concrete to be patterns. A function is a mapping from one set to another. Even category theory manages to fully generalize functions several different ways without managing to define something as general as a pattern.

So, you might ask, what are patterns? Patterns are things which repeat somehow. That's it. There might be more to it, but I have yet to find it.

I'm glad that you like Lisp, but it's not the beginning nor the end of programming. For example, the Post correspondence problem is Turing-complete. So are Wang tiles. Where's your functions now?