F# return ICollection

Question

I\'m working with a library created in C#. I\'ve been working on porting some code to F# but must use quite a few underlying types from the C# lib.

One piece of code

Answer 1

F# doesn't do implicit casting like C#. So even though System.Collections.Generic.List<'T> implements the ICollection interface, you can't directly set some ICollection-typed property to an instance of System.Collections.Generic.List<'T>.

The fix is easy though -- all you need to do is add an explicit upcast to ICollection to your ResizeArray<'T> or System.Collections.Generic.List<'T> before assigning it:

// Make sure to add an 'open' declaration for System.Collections.Generic
this.field.Collection1 = (recoveries :> ICollection)

or

this.field.Collection1 = (ResizeArray<Recoveries>() :> ICollection)