We must be careful with terms like readable, user-friendly, and so forth. They are vague at best, and often refer to taste and established habits. But what is conventional need not also be convenient. In the context of programming languages, perhaps "readable" should be replaced by "amenable to formal reasoning." For example, mathematical formulas are hardly what we might praise as easily readable, but they allow the formal derivation of properties that could not be obtained from a vague, fuzzy, informal, user-friendly circumscription.