[rlmark]

That's a great question! (I work for Unison, full disclosure.)

The process for upgrading Unison code is that if you have a function A that calls B, and you update B in some way, as long as the change is type-preserving it will automatically be propagated to all the sites in your project where B is called. If the change is not type-preserving (for example, if you added a parameter) the tooling itself will direct you to resolve all the places where B is applied. So as you change code locally, you're continually keeping your codebase in sync; A will always be calling the updated function.

Here's an example from our docs: https://www.unison-lang.org/docs/usage-topics/workflow-how-t...