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> There's a reason OO and UI have been married together for decades. People repeat this a lot, that OO goes with UI, but I don't think it's actually true, and

> There's a reason OO and UI have been married together for decades. People repeat this a lot, that OO goes with UI, but I don't think it's actually true, and I think e.g. React Hooks and immediate mode GUI in general demonstrate that it's not true. OO has been coupled with UI out of inertia, not because OO has unique strengths when applied to UI. Sum types are a primitive language feature, akin to product types, which absolutely no one rejects the value of. The sum/product analogy to arithmetic is compelling to me: they are the building blocks of complex types and deserve recognition. I think that "zen koan" you mentioned earlier is being very generous to subclassing. You want ADTs most of the time!

munificent 7y ago
> People repeat this a lot, that OO goes with UI, but I don't think it's actually true It is evidentially true. Thousands of successful applications and a billions of lines of UI code have been written in object oriented languages. It does work and it can't be that bad if that's continuing to happen even after the emergence of other alternatives. Whether there are better ways is a good question, but I think it's pretty clear that you can ship good apps using OOP for your UI. > React Hooks and immediate mode GUI in general demonstrate that it's not true. I'm far enough into my career now — I've been doing UI programming of one form or another since the 90s — to have seen that pendulum swing several times. If there is a silver bullet, we haven't found it. It's probably not immediate mode GUIs because if it was, I wouldn't have seen game teams tear them out to replace them with something more retained several times in the 2000s. What I think actually happens is that we forget the problems lurking in the solution we are not currently using. The grass over there gets greener and greener until we hop the fence and the cycle starts over. Incremental progress does happen. (I am not keen to revisit MFC any time soon.) But if a given concept (1) has been around a long time (2) has not already supplanted the alternatives, it's pretty unlikely that it is now an amazing solution today. The only time when that isn't true is when the surrounding technology context has changed since then. For example, neural nets weren't a good solution for AI problems in the 80s because compute was too expensive and we didn't have a lot of data. Now that CPUs are cheap and everyone puts their entire life on the Internet, machine learning is here. I haven't seen anything around UIs that to me looks like a significantly changed context, so I think we're still orbiting around retained-mode and immediate-mode as both having their own trade-offs and neither being a slam dunk. > I think that "zen koan" you mentioned earlier is being very generous to subclassing. You want ADTs most of the time! I really don't think that's true. Just look out there in the world. More code is written in languages doing subclassing every day than in languages with sum types. Despite the fact that sum types have been around since the 70s. You have to have a very uncharitable opinion of all of your fellow programmers to believe they've all been getting this wrong for decades. Heck, the software you are using right now to read this comment is sitting on a stack of several layers of subclass-based architectures! You've got JS running on top of the DOM inside a browser written in C++. Sum types are really nice. But open-ended subclassing is too.
- xkapastel 7y ago
  First, I just want to say that I use Dart pretty regularly now and enjoy the language. I don't want to come across as overly negative; Dart is a solid language that's made web programming a lot more fun for me. So thank you, and everyone else on the Dart team for the hard work! I just want to address these lines: > Thousands of successful applications and a billions of lines of UI code have been written in object oriented languages. > More code is written in languages doing subclassing every day than in languages with sum types. Despite the fact that sum types have been around since the 70s. You have to have a very uncharitable opinion of all of your fellow programmers to believe they've all been getting this wrong for decades. I agree that there's a huge amount of code out there using subclassing and not sum types. I'm not disputing the utility of subclassing; I just think the analogy to arithmetic is compelling, in that a closed sum type is a more primitive notion than open ended subclassing. It's easier to describe what a sum type is than what a subclass is; sum types have a smaller impact on a type system than subclassing. Pretty much any metric you can think of, sum types are just simpler, and more widely applicable. Any time you are describing a data structure, an ADT is immediately useful; subtyping may or may not be useful and is always more complicated. It's very difficult for me to understand how anyone could possibly say subtyping is on the same level as a basic operation like addition. Subclassing may or may not be nice but sum types are a primitive in a way that subclassing simply cannot be. I don't know how to break it down more than this: we already have multiplication of types, and everyone accepts this as a primitive. Well, you can also do addition of types! Multiplication, addition, a neat little pair, just like algebra class[0]. Subclassing is way more complicated than this. That's it, that's a bullet proof argument as far as I'm concerned. I suppose I do have an uncharitable opinion of mainstream programming languages, because I do think they've been getting this wrong for decades. It's nothing personal, it's just that industry has other concerns besides how clean their languages are. My browser being written in C++ is not an argument in favor of subclassing, though. You can build anything out of toothpicks if you're paid enough. [0]: https://typedefs.com/introduction/ https://typedefs.com/introduction/
  - munificent 7y ago
    > I just think the analogy to arithmetic is compelling, in that a closed sum type is a more primitive notion than open ending subclassing. I agree, sum types have a real beautiful elegance. But I often wonder if that's some sort of "appeal to mathematical aesthetics" fallacy. When I see, for example, painters deciding what brushes to use, I don't see them choosing brushes whose diameter follows the Fibonacci sequence or something. 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. > Any time you are describing a data structure, an ADT is immediately useful For what it's worth, I often run into problems where I think I can map something to a nice set of ADTs but then it ends up still having ugly corners. As elegant as the language feels, when I use them in practice my code is still awkward sometimes. > It's very difficult for me to understand how anyone could possibly say subtyping is on the same level as basic operation like addition, one of them is clearly a more basic idea. Subtyping is set theory, and sets are obviously more fundamental than arithmetic! :D > we already have multiplication of types, and everyone accepts this as a primitive. Well, actually, lots of languages don't have tuples and records/structs aren't simple product types. > I suppose I do have an uncharitable opinion of mainstream programming languages I wasn't talking about languages I was talking about people. There are languages out there with all of the features you describe. Yet millions of people are choosing other languages. 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.

munificent 7y ago

> People repeat this a lot, that OO goes with UI, but I don't think it's actually true It is evidentially true. Thousands of successful applications and a billions of lines of UI code have been written in object oriented languages. It does work and it can't be that bad if that's continuing to happen even after the emergence of other alternatives. Whether there are better ways is a good question, but I think it's pretty clear that you can ship good apps using OOP for your UI. > React Hooks and immediate mode GUI in general demonstrate that it's not true. I'm far enough into my career now — I've been doing UI programming of one form or another since the 90s — to have seen that pendulum swing several times. If there is a silver bullet, we haven't found it. It's probably not immediate mode GUIs because if it was, I wouldn't have seen game teams tear them out to replace them with something more retained several times in the 2000s. What I think actually happens is that we forget the problems lurking in the solution we are not currently using. The grass over there gets greener and greener until we hop the fence and the cycle starts over. Incremental progress does happen. (I am not keen to revisit MFC any time soon.) But if a given concept (1) has been around a long time (2) has not already supplanted the alternatives, it's pretty unlikely that it is now an amazing solution today. The only time when that isn't true is when the surrounding technology context has changed since then. For example, neural nets weren't a good solution for AI problems in the 80s because compute was too expensive and we didn't have a lot of data. Now that CPUs are cheap and everyone puts their entire life on the Internet, machine learning is here. I haven't seen anything around UIs that to me looks like a significantly changed context, so I think we're still orbiting around retained-mode and immediate-mode as both having their own trade-offs and neither being a slam dunk. > I think that "zen koan" you mentioned earlier is being very generous to subclassing. You want ADTs most of the time! I really don't think that's true. Just look out there in the world. More code is written in languages doing subclassing every day than in languages with sum types. Despite the fact that sum types have been around since the 70s. You have to have a very uncharitable opinion of all of your fellow programmers to believe they've all been getting this wrong for decades. Heck, the software you are using right now to read this comment is sitting on a stack of several layers of subclass-based architectures! You've got JS running on top of the DOM inside a browser written in C++. Sum types are really nice. But open-ended subclassing is too.

xkapastel 7y ago
First, I just want to say that I use Dart pretty regularly now and enjoy the language. I don't want to come across as overly negative; Dart is a solid language that's made web programming a lot more fun for me. So thank you, and everyone else on the Dart team for the hard work! I just want to address these lines: > Thousands of successful applications and a billions of lines of UI code have been written in object oriented languages. > More code is written in languages doing subclassing every day than in languages with sum types. Despite the fact that sum types have been around since the 70s. You have to have a very uncharitable opinion of all of your fellow programmers to believe they've all been getting this wrong for decades. I agree that there's a huge amount of code out there using subclassing and not sum types. I'm not disputing the utility of subclassing; I just think the analogy to arithmetic is compelling, in that a closed sum type is a more primitive notion than open ended subclassing. It's easier to describe what a sum type is than what a subclass is; sum types have a smaller impact on a type system than subclassing. Pretty much any metric you can think of, sum types are just simpler, and more widely applicable. Any time you are describing a data structure, an ADT is immediately useful; subtyping may or may not be useful and is always more complicated. It's very difficult for me to understand how anyone could possibly say subtyping is on the same level as a basic operation like addition. Subclassing may or may not be nice but sum types are a primitive in a way that subclassing simply cannot be. I don't know how to break it down more than this: we already have multiplication of types, and everyone accepts this as a primitive. Well, you can also do addition of types! Multiplication, addition, a neat little pair, just like algebra class[0]. Subclassing is way more complicated than this. That's it, that's a bullet proof argument as far as I'm concerned. I suppose I do have an uncharitable opinion of mainstream programming languages, because I do think they've been getting this wrong for decades. It's nothing personal, it's just that industry has other concerns besides how clean their languages are. My browser being written in C++ is not an argument in favor of subclassing, though. You can build anything out of toothpicks if you're paid enough. [0]: https://typedefs.com/introduction/ https://typedefs.com/introduction/
- munificent 7y ago
  > I just think the analogy to arithmetic is compelling, in that a closed sum type is a more primitive notion than open ending subclassing. I agree, sum types have a real beautiful elegance. But I often wonder if that's some sort of "appeal to mathematical aesthetics" fallacy. When I see, for example, painters deciding what brushes to use, I don't see them choosing brushes whose diameter follows the Fibonacci sequence or something. 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. > Any time you are describing a data structure, an ADT is immediately useful For what it's worth, I often run into problems where I think I can map something to a nice set of ADTs but then it ends up still having ugly corners. As elegant as the language feels, when I use them in practice my code is still awkward sometimes. > It's very difficult for me to understand how anyone could possibly say subtyping is on the same level as basic operation like addition, one of them is clearly a more basic idea. Subtyping is set theory, and sets are obviously more fundamental than arithmetic! :D > we already have multiplication of types, and everyone accepts this as a primitive. Well, actually, lots of languages don't have tuples and records/structs aren't simple product types. > I suppose I do have an uncharitable opinion of mainstream programming languages I wasn't talking about languages I was talking about people. There are languages out there with all of the features you describe. Yet millions of people are choosing other languages. 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.