| > Subtyping is set theory, and sets are obviously more fundamental than arithmetic! :D In case this wasn't clear, the "arithmetic" in question is being performed on sets (or types). For example, for sum types, the number of inhabitants of the type is the sum of the inhabitants of the components. All three of addition, multiplication and subtyping are operations on sets (types). So this was a strange thing to say. > Simplicity is a virtue because it lowers the cognitive load of a language. I don't know if mapping something to arithmetic tells us something actually profound about the productivity of a language feature, even if it gives me a little shiver of delight when I think about it. My real point is this: if you are deciding to build a language, as far as I'm concerned, it is very strange to add multiplication (why don't structs count as multiplication? I would say they do), then not add addition and instead add something much more complicated than addition. It just doesn't make any sense. It's not about the "productivity" (how do we measure this?) of the feature, it's about it not making any sense to do this! You add multiplication, you add addition, that's really all there is to it. I don't know, I guess I'm just repeating myself now and you won't find it convincing, but to me it's like trying to defend Roman numerals after being shown the Arabic system. > You must have an uncharitable view of those people if you presume that all of them are making a choice that goes against their own self-interest to be happy productive programmers. I don't think so at all. It's not really a fair choice; people choose languages in order to build things, and it's easier to build things in languages that other people are using. The full range of options is not obvious to every programmer (does the average webdev even know about ML?), and most of the time there are more important concerns than whether your language has a nice theory behind it. |