Returning arrays of different dimensions from one function; is it possible in F#?

Question

I am trying to convert some Python to F#, specifically numpy.random.randn.

The function takes a variable number of int arguments and returns arrays of different dim

Answer 1

Although Tomas' suggestion to use overloading is probably best, .NET arrays do share a common sub-type: System.Array. So what you want is possible.

member self.differntarrays ([<ParamArray>] dimensions: Object[]) : Array =
    match dimensions with
    | [| dim1 |] ->      
         [| 
            1 
         |] :> _
    | [| dim1; dim2 |] -> 
        [|
           [| 2 |], 
           [| 3 |] 
        |] :> _
    | _ -> failwith "error"

Answer 2

You are correct - an array of floats float[] is a different type than array of arrays of floats
float[][] or 2D array of floats float[,] and so you cannot write a function that returns one or the other depending on the input argument.

If you wanted to do something like the Python's rand, you could write an overloaded method:

type Random() = 
  static let rnd = System.Random()
  static member Rand(n) = [| for i in 1 .. n -> rnd.NextDouble() |]
  static member Rand(n1, n2) = [| for i in 1 .. n1 -> Random.Rand(n2) |]
  static member Rand(n1, n2, n3) = [| for i in 1 .. n1 -> Random.Rand(n2, n3) |]