c# - Immutable collections?

Question

I am making most of my basic types in my app, immutable. But should the collections be immutable too? To me, this seems like a huge overhead unless I am missing something.

I am talking about collections to hold Point3 values, etc which can be added as it goes at different times. So if there are 1M values in a collection, and you needed to delete 1 of them, you would have to create the same collection all over again, right?

Answer 1

Eric Lippert has a series on Immutability in C#, and if you read it all the way through he implements a couple different immutable collections:

1. Immutability in C# Part One: Kinds of Immutability
2. Immutability in C# Part Two: A Simple Immutable Stack
3. Immutability in C# Part Three: A Covariant Immutable Stack
4. Immutability in C# Part Four: An Immutable Queue
5. Immutability in C# Part Five: LOLZ!
6. Immutability in C# Part Six: A Simple Binary Tree
7. Immutability in C# Part Seven: More on Binary Trees
8. Immutability in C# Part Eight: Even More On Binary Trees
9. Immutability in C# Part Nine: Academic? Plus my AVL tree implementation
10. Immutability in C# Part Ten: A double-ended queue
11. Immutability in C# Part Eleven: A working double-ended queue