What am I doing wrong in this F# code?

Question

let parallelTest n = Color(Color.DeepPink, Triangles(sphere n));;

Parallel.For(0,10,new Action(parallelTest));;

Error message : error FS0001: Type mismatch. Expecting a int -> unit but given a int -> scene. The type 'unit' does not match the type 'scene'

I'll glad if some body help me.

• Juliet: Based on your code and some of your comments, it looks like you're not fully in the groove of F# programming style. Can you post your code and describe what you actually trying to do?

Answer 1

Compose your function with ignore to make it return unit:

Parallel.For(0, 10, parallelTest >> ignore)

• Angelica: Hi Mauricio, thanks for your help too. It works!!!!!!! But now I need to know how can I return a scene type this for? Thanks again for your help.
• Mauricio Scheffer: Parallel.For doesn't return any value. This might help you: weblogs.asp.net/podwysocki/archive/2009/02/23/… . Create other questions if you have more doubts.

Answer 2

If you want 10 results, perhaps you want

[| for i in 0..9 do
 async { return parallelTest i } |]
|> Async.Parallel
|> Async.RunSynchronously

This will return an array of 10 scene results.

Answer 3

At which position does this error message occur? (I can't reproduce the error since I don't know the delcarations of some functions you use)

I guess the following: Parallel.For expects a int -> unit (Action<int> in standard .NET), but parallelTest has a different type (int -> scene) which is therefore incompatible.

And what are you trying to achieve with the whole code?

• Angelica: Hi Dario, thanks for your help, I'm trying to do surface subdvision in parallel, but I try to use this Parallel.For as a mean to make easy my job to do that version in parallel. Do you have any tips for me to do this easily and in parallel? Thanks again.