What's the best name for a non-mutating “add” method on an immutable collection?

Question

Sorry for the waffly title - if I could come up with a concise title, I wouldn\'t have to ask the question.

Suppose I have an immutable list type. It has an operat

Answer 1

In situations like that, I usually go with Concat. That usually implies to me that a new object is being created.

var p = listA.Concat(listB);
var k = listA.Concat(item);