Question

I have a function in C# that is being called in F#, passing its parameters in a Microsoft.FSharp.Collections.List<object>.

How am I able to get the items from the F# List in the C# function?

EDIT

I have found a ‘functional’ style way to loop through them, and can pass them to a function as below to return C# System.Collection.List:

private static List<object> GetParams(Microsoft.FSharp.Collections.List<object> inparams) {     List<object> parameters = new List<object>();     while (inparams != null)     {         parameters.Add(inparams.Head);         inparams = inparams.Tail;      }      return inparams;  } 

EDIT AGAIN

The F# List, as was pointed out below, is Enumerable, so the above function can be replaced with the line;

new List<LiteralType>(parameters); 

Is there any way, however, to reference an item in the F# list by index?

Answer 1

In general, avoid exposing F#-specific types (like the F# ‘list’ type) to other languages, because the experience is not all that great (as you can see).

An F# list is an IEnumerable, so you can create e.g. a System.Collections.Generic.List from it that way pretty easily.

There is no efficient indexing, as it’s a singly-linked-list and so accessing an arbitrary element is O(n). If you do want that indexing, changing to another data structure is best.