Should I represent database data with immutable or mutable data structures?

Question

I\'m currently programming in Scala, but I guess this applies to any functional programming language, or rather, any programming language that recommends immutability and can in

Answer 1

In the trading app I'm currently working on, almost everything is immutable - certainly the model is.

Our experience is that this has greatly simplified how we work with the model, including persistence.

I don't understand yet why things have become simpler, it just has. I need to ponder on this more. Reasoning about the code and working with it is simpler.

Yes, you need to use things like lenses but I tend to write them - a mechanical process - and move on. It's a tiny part which I am sure can be finessed.