I think the answer to the question "should I apply X refactoring technique to this function Y?" obviously has to depend on both X and Y. There's clearly a trad

I think the answer to the question "should I apply X refactoring technique to this function Y?" obviously has to depend on both X and Y. There's clearly a trade-off here. If I have a free function foo(x) that I want to work differently depending if x is type A or type B, splitting that means breaking up foo, sure, but because I can only ever call foo with an x of type A or type B (unless I'm converting some As to Bs halfway through foo or something awful like that) it might be useful to see all of the "A" logic in one place and all of the "B" logic in another place.