What is the benefit of purely functional data structure?

Question

There are large number of texts on data structures, and libraries of data structures code. I understand that purely functional data structure is easier to reason about. Howe

Answer 1

Take this little snippet of F#:

let numbers = [1; 2; 3; 4; 5]

You can say with 100% certainty that that is a immutable list of integers 1 through 5. You can pass around a reference to that list and never have to worry that the list may have been modified. That is enough reason for me to use it.