> don't mix levels of abstraction I'm uncomfortable about this because abstractions are difficult to define and demarcate - and end up being leaky anyway. So y

> don't mix levels of abstraction I'm uncomfortable about this because abstractions are difficult to define and demarcate - and end up being leaky anyway. So you need to change several separate functions in parallel, instead of having them in the same place. OTOH there are also some obviously different levels of abstraction, which it makes sense not to mix. Further, some such levels can be established in a particular domain, so whether good or not, they are helpful for people already trained in or familiar with that domain.