[logistark]

For me, protocols i tend to not use it, because it makes it harder to understand the code and Cursive cannot find instances that implements the protocols.

For testing purposes is easier to redef a function than implementing a full new test protocol.

[yogthos]

I agree that in most cases with-redefs works fine, and I tend to use protocols sparingly myself for the same reasons.

I thought it was worth mentioning that you can use them to encapsulate any effectful code since they can be used as a tool to help enforce a bit of discipline. If you're just calling functions that can cause side effects then it can get tricky to figure out what all the functions that need to be redefined are. You basically have to read through all the code to know what you need to mock. If you stick all the side effects in a protocol, then you're being very explicit about what needs to be mocked out.