I think Library APIs are a good example. I've found myself in the situation where I do not care about the string representation (or can convert in a few places

I think Library APIs are a good example. I've found myself in the situation where I do not care about the string representation (or can convert in a few places if necessary), but need to provide an interface for others that is as frictionless as possible. My instinct there was to be generic and use From/To traits, but it never felt quite right.