How to implement LINQ functions in a VB.NET collection class - vb.net

Question

I have a collection class which is a wrapper for a
List(Of MyClass)
And the collection class implements things like add, count etc
Private lst As List(Of MyClass)
Public Function Count() As Long
Return lst.Count
End Function
I want to add the ability to do Linq queries on the collection class. So client could do something like this:
dim c as New MyCollectionClass
c.Add(New MyClass With {.Name = "XXX"})
c.Add(New MyClass With {.Name = "XXX"})
c.Add(New MyClass With {.Name = "YYYY"})
Dim nc As MyCollectionClass = c.GroupBy(function(x) x.Name)
How do I implement the groupby function and all the other Linq functions (select, filter, distinct, orderby etc) ? I've implemented iQueryable in the class.
I'm confused on how to declare it and its parameters and implementation etc. I've tried a few things like
Public Function GroupBy(f As Func(Of MyClass)) As IEnumerable
Return lst.GroupBy(Function(x As MyClass) f(x))
End Function
But thats just a syntax error, and I'm just stuck now :) thanks
FWIW this is what I've done for Iqueryable:
Implements IEnumerable, IQueryable
Private lst As New List(Of MyClass)
Public ReadOnly Property Expression As Expression Implements IQueryable.Expression
Get
Return lst.AsQueryable.Expression
End Get
End Property
Public ReadOnly Property ElementType As Type Implements IQueryable.ElementType
Get
Return lst.AsQueryable.ElementType
End Get
End Property
Public ReadOnly Property Provider As IQueryProvider Implements IQueryable.Provider
Get
Return lst.AsQueryable.Provider
End Get
End Property

Answer 1

You don't need to re-implement Linq extensions (Select, GroupBy, etc.). You just need to implement IEnumerable(Of MyClass), then standard Linq extensions will work with your class automatically.
An example of IEnumerable(Of ...) implementation:
Public Class MyCollection
Implements IEnumerable(Of MyClass1)
Private lst As New List(Of MyClass1)
Public Function GetEnumerator() As IEnumerator(Of MyClass1) Implements IEnumerable(Of MyClass1).GetEnumerator
Return lst.GetEnumerator()
End Function
Private Function IEnumerable_GetEnumerator() As IEnumerator Implements IEnumerable.GetEnumerator
Return DirectCast(lst, IEnumerable).GetEnumerator()
End Function
End Class
And usage:
Dim collection = New MyCollection
...
Dim count = collection.Count()