"A Philosophy of Software Design" by John Ousterhout talks about the costs of introducing abstractions, with the implication that modules should be "narrow and

"A Philosophy of Software Design" by John Ousterhout talks about the costs of introducing abstractions, with the implication that modules should be "narrow and deep". The width is defined as the size of the interface (the cost) and the depth as the functionality that it buys you or maybe the complexity it hides (I'm recalling from memory, don't have the book at hand). A file system that exposes the file interface (as in Unix) is given as a positive example. It has few functions and buys you, well, everything a file system offers.