[YeGoblynQueenne]

Recursion is frequently used as progressive iteration, but it can go further than that.

Typical example, a factorial function, in Erlang:

  factorial(N) -> 
	factorial(N,1).

  factorial(0, F) -> F;
  factorial(N, F) -> 
	factorial(N-1, N*F).

It's strange to read that as iteration. Instead it feels natural to describe it as composition from parts that are of the same kind as the whole.

[posterboy]

of course that is some kind of iteration because tail recursion is isomorphic to loops and that N-1 sure looks like a while(--N)

[YeGoblynQueenne]

I'm not sure I know what "isomorphic" means in this context.

For sure, (tail) recursion places a pointer to a function on the stack while a loop is a conditional jump. They're not the same thing. I think the similarity between n-1 and --n is a red herring, here.