Pass a lambda expression in place of IComparer or IEqualityComparer or any single-method interface?

Question

I happened to have seen some code where this guy passed a lambda expression to a ArrayList.Sort(IComparer here) or a IEnumerable.SequenceEqual(IEnumerable list, IEqualityCom

Answer 1

These methods don't have overloads that accept a delegate instead of an interface, but:

• You can normally return a simpler sort key through the delegate you pass to Enumerable.OrderBy
• Likewise, you could call Enumerable.Select before calling Enumerable.SequenceEqual
• It should be straightforward to write a wrapper that implements IEqualityComparer in terms of Func
• F# lets you implement this sort of interface in terms of a lambda :)