Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

The Java type system is broken

wouter.coekaerts.be

Post reply on HN
Print view View original

21–30 of 168 posts

Re: The Java type system is broken

#21

Post by hyperpape »

buremba wrote: post #10

Welcome to the world of enterprise-ready complex applications. I agree that these cases should be covered by the compiler but man, there are mainstream languages that don't implement generics just because they're complex and pretend that they're not helpful. It would be nice of you to compare Java generics with equivalents instead of just criticizing it. It doesn't help anyone writing "this is broken" not offering an…

I think it would've been better to write "unsound" rather than broken, but it's pretty common to present little proofs/results like this without saying how the system should fix it. Doing so is helpful, because many times you'll know there's a problem without there being an obvious fix.

Re: The Java type system is broken

#22

Post by pdpi »

buremba wrote: post #10

Welcome to the world of enterprise-ready complex applications. I agree that these cases should be covered by the compiler but man, there are mainstream languages that don't implement generics just because they're complex and pretend that they're not helpful. It would be nice of you to compare Java generics with equivalents instead of just criticizing it. It doesn't help anyone writing "this is broken" not offering an…

Clearly you didn't reach the conclusion. First, because the conclusion is not "Java sucks", but rather "Most of these things, while not kosher, are unlikely to happen in practice." Second, because the author didn't just leave it at criticising the language — he opened a bunch of bugs in the OpenJDK tracker.

Re: The Java type system is broken

#23

Post by moron4hire »

TazeTSchnitzel wrote: post #5

My favourite feature of Java's type system is that, because any object type also accepts null, the type system is unsound and you can convert anything to anything else: https://raw.githubusercontent.com/namin/unsound/master/doc/u...

It should be noted that soundness is not a common feature for type systems in the wild. It sounds kind of scary, "X programming language's type system is unsound", but that's pretty much been the status quo for most of programming.

Re: The Java type system is broken

#24

Post by sorokod »

rimunroe wrote: post #7
viach wrote: post #4

From the examples: "String s = gridWrapper.get(0).get(0).get(0);" - Java type system is broken! Java is not perfect, but this looks to me like a broken code indeed ".get(0).get(0).get(0)". Could we rephrase the message of the article as "If you write really broken code in Java, you might be not guarded by the type system". And this is, well, uhm, well... acceptable?

Is a type system really worth that much if it can't help you in a situation where your code is ugly and hard to follow?

Type system helps those who help themselves.

Re: The Java type system is broken

#25

Post by stickfigure »

rimunroe wrote: post #7
viach wrote: post #4

From the examples: "String s = gridWrapper.get(0).get(0).get(0);" - Java type system is broken! Java is not perfect, but this looks to me like a broken code indeed ".get(0).get(0).get(0)". Could we rephrase the message of the article as "If you write really broken code in Java, you might be not guarded by the type system". And this is, well, uhm, well... acceptable?

Is a type system really worth that much if it can't help you in a situation where your code is ugly and hard to follow?

Unequivocally, yes.

Several new languages (eg Typescript, Dart) have optional type systems that still bring significant value to the table.

Sure - all other things being equal, I'd much rather have a type system that is completely sound. Ceylon's type system is beautiful and I'm happy to see its union + intersection types being adopted by Typescript. But honestly, I'm not going to lose much sleep over these particular issues in Java. Bad code gets refactored.

A bigger complaint should be made that generic type erasure makes libraries hard (eg, the number of places you have to pass around Class or TypeReference objects to let the runtime know what to do). But that was a clearly a compromise decision and everyone knows about it.

Re: The Java type system is broken

#26

Post by bad_user »

pdpi wrote: post #22
buremba wrote: post #10

Welcome to the world of enterprise-ready complex applications. I agree that these cases should be covered by the compiler but man, there are mainstream languages that don't implement generics just because they're complex and pretend that they're not helpful. It would be nice of you to compare Java generics with equivalents instead of just criticizing it. It doesn't help anyone writing "this is broken" not offering an…

Clearly you didn't reach the conclusion. First, because the conclusion is not "Java sucks", but rather "Most of these things, while not kosher, are unlikely to happen in practice." Second, because the author didn't just leave it at criticising the language — he opened a bunch of bugs in the OpenJDK tracker.

People criticizing constructive criticism are often not constructive.

Re: The Java type system is broken

#27

Post by Doxterpepper »

viach wrote: post #4

From the examples: "String s = gridWrapper.get(0).get(0).get(0);" - Java type system is broken! Java is not perfect, but this looks to me like a broken code indeed ".get(0).get(0).get(0)". Could we rephrase the message of the article as "If you write really broken code in Java, you might be not guarded by the type system". And this is, well, uhm, well... acceptable?

What's the point of strong typing if it only saves you most of the time?

Re: The Java type system is broken

#28

Post by bad_user »

It’s pretty tragic how people respond to such criticism emotionally, instead of acknowledging the issues and working towards fixing them or educating others in the traps and compromises involved.

HN is less prone to toxicity, but this is reminiscent of Reddit and it drives away the people that want to help.

As a piece of advice, some type theory never harmed anyone ;-)

Re: The Java type system is broken

#29

Post by kochthesecond »

moron4hire wrote: post #23
TazeTSchnitzel wrote: post #5

My favourite feature of Java's type system is that, because any object type also accepts null, the type system is unsound and you can convert anything to anything else: https://raw.githubusercontent.com/namin/unsound/master/doc/u...

It should be noted that soundness is not a common feature for type systems in the wild. It sounds kind of scary, "X programming language's type system is unsound", but that's pretty much been the status quo for most of programming.

I was about to say this. Most type systems in practical use are not mathematically sound.

Re: The Java type system is broken

#30

Post by emodendroket »

opnitro wrote: post #18
viach wrote: post #4

From the examples: "String s = gridWrapper.get(0).get(0).get(0);" - Java type system is broken! Java is not perfect, but this looks to me like a broken code indeed ".get(0).get(0).get(0)". Could we rephrase the message of the article as "If you write really broken code in Java, you might be not guarded by the type system". And this is, well, uhm, well... acceptable?

Is it? The whole point of a type system is that it gives you guarantees over your code. Certain bugs should be inexpressible within the language.

Well, think of it this way. A seat belt cannot help you at all if an object flies through your windshield. Nevertheless, driving while wearing a seat belt is, overall, safer than driving without one.
Post reply on HN