I have a problem with writing a Cartesian power function. I found many examples about calculating Cartesian Product, but no one about Cartesian power.
For example, [1;2] raised to power 3 = [ [1;1;1] ; [1;1;2] ; [1;2;1] ; [1;2;2] ; [2;1;1] ; [2;1;2] ; [2;2;1]; [2;2;2] ]
I use following code to calculate Cartesian Product:

 let Cprod U V =
        let mutable res = []
        for u in U do
            for v in V do
                res <- res @ [[u;v]]
        res

And trying to calculate Cartesian power. I use following code to calculate Cartesian Product:

let Cpower U n =
    let mutable V = U
    for i=0 to n-1 do
        V <- Dprod U V
    V

Visual Studio said: Error The resulting type would be infinite when unifying ''a' and ''a list'. I will thankful for any help and links.