Hi, I'm writing a module that contains a data type for a MacAddress. Given that, I can do things like validate and format. But there are several ways you can display a MacAddress: 'aabbccddeeff' or '00:11:22:33:AA:BB' or 'aa:bb:cc:00:11:22'. Different external systems want the mac addresses in different formats, and I'd like to centralize that logic. ** So the design question: I can't just use a `show` function directly to do this, since there are options I need to pass. I could use separate functions that return a string. I could use newtype to wrap each display style of mac address in a type that has a specific `show` instance that spits out the right format. So a `Pretty` and `Lower` and similar types. --- Is there a best-practice here? Am I totally missing a better way to model this idea?