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Chris Lattner on the Realm WWDC 2017 Swift Panel

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Re: Chris Lattner on the Realm WWDC 2017 Swift Panel

#71

Post by willtim »

yiransheng wrote: post #67
legulere wrote: post #11

Earlier quoted context omitted.

The issues with inheritance based OOP are that it fits very few problems well, that it usually causes lots of problems and that many programming languages only have inheritance based OOP in their toolbox. Java is the extreme case of this. Patterns like abstract visitor factories are hacks to express situations that cannot be expressed in an obvious way.

Inheritance based OOP models tree-like entites well, where hirachy is defined and clear cut. Unfortunately, lots of real life domains are best expressed by graphs - commonly a DAG. You need to pay attention to your edges and not just the nodes. Inheritance based OOP gives you one keyword to express your edges: extend, and it's horribly inadequate. Mutatable state is not a issue in Java OOP, lacking the expressive pow…

Trees can be modelled with sum types, the mathematical dual of product types (records). Java doesn't have sum types and so inheritance has to be used to encode them.

Re: Chris Lattner on the Realm WWDC 2017 Swift Panel

#72

Post by willtim »

smaili wrote: post #10

> What irritates me is when people say classes are bad. Or subclassing is bad. Thatʼs totally false. Classes are super important. Reference semantics are super important. If anything, the thing thatʼs wrong is to say, one thing is bad and the other thing is good. These are all different tools in our toolbox, and theyʼre used to solve different kinds of problems. Couldn't agree more

Subtyping adds huge amounts of complexity to type systems and type inference. Dart even chose to have an unsound type system because subtyping and parametric polymorphism (generics in Java) were deemed too hard for Google programmers to understand. The Go designers agreed. Haskell and OCaml are a joy to program in, in part because they (mostly) eschew subtyping. So yes, subtyping is controversial.

Re: Chris Lattner on the Realm WWDC 2017 Swift Panel

#73

Post by comex »

KKKKkkkk1 wrote: post #57
valuearb wrote: post #4

Earlier quoted context omitted.

As someone who spent over 20 years writing applications in C, anything built on C is crap and that includes C++ and Objective C. Writing code is fun and interesting. But most software development is not writing code. It's a little bit of build management, even more testing, but mostly it's debugging. Debugging is not as fun as writing code. Every language feature that makes debugging more necessary, harder to do and…

With Valgrind, I would say dangling pointers are a solved problem by now. The real debugging headaches in C++ come from stuff like autogenerated constructors, overloading, template specialization, and other features that change semantics without requiring the syntax of the code that experiences the change to reflect that change. My unpopular opinion is that exceptions also fall into this class of dark features.

> With Valgrind, I would say dangling pointers are a solved problem by now.

Given the frequency with which use-after-free vulnerabilities are discovered in C++ programs, I’d say they’re not a solved problem. Valgrind is great but it doesn’t help when the only inputs that cause bad behavior are bizarre attacker-generated ones.

Re: Chris Lattner on the Realm WWDC 2017 Swift Panel

#74

Post by coldtea »

>Look at Javascript or any of these other languages out there. They started with a simple premise (“I want to do simple scripting in a web browser”) and now people are writing freaking server apps in it. What happened there? Is there a logical leap that was missed? How is this a good idea? [Audience laughs] Sorry, I love Javascript too. Iʼd just love to kill it even more.

Emphasis mine. Not that I disagree completely...

Re: Chris Lattner on the Realm WWDC 2017 Swift Panel

#75

Post by coldtea »

willtim wrote: post #72
smaili wrote: post #10

> What irritates me is when people say classes are bad. Or subclassing is bad. Thatʼs totally false. Classes are super important. Reference semantics are super important. If anything, the thing thatʼs wrong is to say, one thing is bad and the other thing is good. These are all different tools in our toolbox, and theyʼre used to solve different kinds of problems. Couldn't agree more

Subtyping adds huge amounts of complexity to type systems and type inference. Dart even chose to have an unsound type system because subtyping and parametric polymorphism (generics in Java) were deemed too hard for Google programmers to understand. The Go designers agreed. Haskell and OCaml are a joy to program in, in part because they (mostly) eschew subtyping. So yes, subtyping is controversial.

>Dart even chose to have an unsound type system because subtyping and parametric polymorphism (generics in Java) were deemed too hard for Google programmers to understand. The Go designers agreed.

And they were both wrong, as millions of programmers use Java and C# and C++ just fine, and have created much more impressive software than what Dart or Golang programmers have. Plus, people used to the power of C++ would never switch to Golang (which is also what the Golang team observed: they mostly got people from Python/Ruby and that kind of services).

>Haskell and OCaml are a joy to program in, in part because they (mostly) eschew subtyping.

Sorry, but did you just said that "subtyping and parametric polymorphism (generics in Java) were deemed too hard for Google programmers to understand" (an argument based on complexity) and then went on to argue in favor of Haskell, which is notoriously difficult to grasp, and has so many foreign concepts that it makes Generics look like BASIC level concepts.

Re: Chris Lattner on the Realm WWDC 2017 Swift Panel

#76

Post by mpweiher »

legulere wrote: post #11
smaili wrote: post #10

> What irritates me is when people say classes are bad. Or subclassing is bad. Thatʼs totally false. Classes are super important. Reference semantics are super important. If anything, the thing thatʼs wrong is to say, one thing is bad and the other thing is good. These are all different tools in our toolbox, and theyʼre used to solve different kinds of problems. Couldn't agree more

The issues with inheritance based OOP are that it fits very few problems well, that it usually causes lots of problems and that many programming languages only have inheritance based OOP in their toolbox. Java is the extreme case of this. Patterns like abstract visitor factories are hacks to express situations that cannot be expressed in an obvious way.

> inheritance based OOP

What's "inheritance based OOP"? The kind of OOP that models everything using subclassing? Partly due to structural static typing so compatibility/polymorphism can only be achieved by having a common ancestor class?

Sure, but that's missing the point of OOP almost completely.

Anyway, subclassing is an extremely useful and by now somewhat underrated tool: it allows for unanticipated extension and programming-by-difference. Meaning you already have something that's close to but not quite what you need.

Re: Chris Lattner on the Realm WWDC 2017 Swift Panel

#77

Post by coldtea »

pjmlp wrote: post #20
geodel wrote: post #7

Interesting interview. Java is mentioned many times as language Swift aspires to replace. He is right about Kotlin: "Kotlin is very reference semantics, itʼs a thin layer on top of Java, and so it perpetuates through a lot of the Javaisms in its model. If we had done an analog to that for Objective-C it would be like, everything is an NSObject and itʼs objc_msgSend everywhere, just with parentheses instead of square…

For that to happen Swift needs to be usable at Java level in all OSes where JVM/JDKs (some of them with AOT support since the early days of Java) do exist. I am still waiting for first class support on Windows on the download page. Right now Rust has much better OS support than Swift.

>For that to happen Swift needs to be usable at Java level in all OSes where JVM/JDKs (some of them with AOT support since the early days of Java) do exist.

No, you seem to confuse "replace Java" with "TOTALLY AND ABSOLUTELY replace Java everywhere".

Swift just needs to be usable on the platforms that matter -- and since it's by default on OS X, that leaves Windows and Linux.

Nobody cares if it runs on some mainframe architecture that 0.001 of Java use happens, or some other obscure environment.

Re: Chris Lattner on the Realm WWDC 2017 Swift Panel

#78

Post by coldtea »

hellofunk wrote: post #2

Wow, he just really really does not like C++. He is certainly an extremely knowledgeable C++ guy, obviously Swift is written in C++, but it's hard to entirely agree with his opinion on it across all fronts.

>He is certainly an extremely knowledgeable C++ guy, obviously Swift is written in C++

Well, he has written not just LLVM in C++, but also a C++ compiler in it (Clang), besides having written Swift in C++.

So that's as far as knowing C++ one can go I'd say.

Re: Chris Lattner on the Realm WWDC 2017 Swift Panel

#79

Post by willtim »

coldtea wrote: post #75
willtim wrote: post #72

Earlier quoted context omitted.

Subtyping adds huge amounts of complexity to type systems and type inference. Dart even chose to have an unsound type system because subtyping and parametric polymorphism (generics in Java) were deemed too hard for Google programmers to understand. The Go designers agreed. Haskell and OCaml are a joy to program in, in part because they (mostly) eschew subtyping. So yes, subtyping is controversial.

> Dart even chose to have an unsound type system because subtyping and parametric polymorphism (generics in Java) were deemed too hard for Google programmers to understand. The Go designers agreed. And they were both wrong, as millions of programmers use Java and C# and C++ just fine, and have created much more impressive software than what Dart or Golang programmers have. Plus, people used to the power of C++ would…

Ignoring all the abstractions and concepts (made possible by underlying simplicity), Haskell is absolutely a simpler language than C++ or Java with Generics.

EDIT: my point was that subtyping is controversial, I assume the downvotes are for my own personal position.

Re: Chris Lattner on the Realm WWDC 2017 Swift Panel

#80

Post by coldtea »

willtim wrote: post #79
coldtea wrote: post #75

Earlier quoted context omitted.

> Dart even chose to have an unsound type system because subtyping and parametric polymorphism (generics in Java) were deemed too hard for Google programmers to understand. The Go designers agreed. And they were both wrong, as millions of programmers use Java and C# and C++ just fine, and have created much more impressive software than what Dart or Golang programmers have. Plus, people used to the power of C++ would…

Ignoring all the abstractions and concepts (made possible by underlying simplicity), Haskell is absolutely a simpler language than C++ or Java with Generics. EDIT: my point was that subtyping is controversial, I assume the downvotes are for my own personal position.

Many people who've tried to get into it, and whose horror stories we read on HN frequently, would argue otherwise.
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