[mordechai9000]

Just curious, I'm not familiar with Go. Will it copy the references anyway, meaning both structures now have a pointer to the same object? That's the way it works in other languages I'm familiar with, so you have to be careful about what you copy and how you use it.

[tonyhb]

Yes, but it doesn't actually matter. You can use pointers for models, return the same pointer, and it will re-render fine. We do this for our CLI at https://www.inngest.com for creating new serverless functions via a quick walkthrough.

It's actually the `tea.Msg` that causes re-renders. Here's the code: https://github.com/charmbracelet/bubbletea/blob/v0.20.0/tea.....

tea.Msg is, in Redux land, an "action" that triggers some state updates and _always_ triggers a re-render, even if nothing changes.

This is elm-like, but we have to understand the limitations of what we're working with: a terminal with no way of (nicely) updating elements in place. It's essentially an immediate-mode UI, and so it always paints.

[sriram_malhar]

Well, it does matter, or rather, it could matter.

For example, say you needed an undo/redo mechanism. If the model were guaranteed to be immutable model, you could simply hang on to the previous models as a sequence of state changes; undoing/redoing is trivial. If the model is mutable, then the undo/redo system has to defensively make a copy before update is called

[christianrocha]

Do note, however, that paints will only occur if the output changes, and only lines that have changed will be redrawn.

[kgeist]

>Will it copy the references anyway, meaning both structures now have a pointer to the same object?

Correct. A value copy is a simple shallow copy. Deep copy requires use of reflection (if you don't want to manually manage copying).

[arccy]

yes, that's what it does in go