Are there any mixin tutorials?

[ixid]

Or any other appropriate methods to achieve things like:

Loop unrolling
foreach(i;0..12)
        //stuff involving the value

And making multiple functions with different values:
func1(int a) {//stuff}
func2(int a) {//stuff}
func3(int a) {//stuff}

where func 1 to 3 are all generated at compile time using the
same template and different values in their function bodies. I'm
trying to make sense of the docs for this but it's not very clear.