Go generics are not bad • Hacker News Board

Re: Go generics are not bad

#21

Post by saagarjha » Fri, Jul 08, 2022, 11:11 PM UTC

margalabargala wrote: post #17

saagarjha wrote: post #11

This is like the most cherry-picked example that could've been chosen. Java can't do this because the primitive types are not objects. Mentioning the performance of this is hilarious because 1. it's Daniel Lemire, he should know better and 2. the performance of pretty much every other thing that uses generics is terrible because of gcshapes being passed everywhere and 3. Java literally has a JIT to make generics fast…

Most things first exist, then exist and are good. We've seen the start of Go generics existing, but we haven't seen them be as good or as fast as they will ever be. Five years from now, Go will still exist. The implementation of generics in that future version of Go is likely to be much faster and better than what we currently have. Put a different way, "Generics are slow in Go v1.18"

I'm hopeful, but the blog post doesn't say "Go generics have room to improve", it says "they're not bad". And they kind of are right now. I can see a road to how they can get better but it's not really very honest to present just this example as indicative of how they work.

Re: Go generics are not bad

#22

Post by google234123 » Fri, Jul 08, 2022, 11:15 PM UTC

saagarjha wrote: post #11

This is like the most cherry-picked example that could've been chosen. Java can't do this because the primitive types are not objects. Mentioning the performance of this is hilarious because 1. it's Daniel Lemire, he should know better and 2. the performance of pretty much every other thing that uses generics is terrible because of gcshapes being passed everywhere and 3. Java literally has a JIT to make generics fast…

You should write a comment on his post - he will probably respond.

Re: Go generics are not bad

#23

Post by thegeekpirate » Fri, Jul 08, 2022, 11:19 PM UTC

drdaeman wrote: post #19

Thaxll wrote: post #15

Earlier quoted context omitted.

How can Go does it even worse that Java where generics implementation is the worse of all modern language with type erasure. Java is way worse than Go on that aspect.

For example, by not allowing one to create a parametrized method. `func (self SomeNonGenericType) Foo[T any](param T) T` is not allowed, best one can do is `func Foo[T any](self SomeNonGenericType, param T) T`. The reasons are explained here: https://go.googlesource.com/proposal/+/refs/heads/master/des... but the point is, you can have this in Java, but not in Go.

You can certainly use generic parameters in methods—the [T any] just has to be on SomeNonGenericType, even if it's not used inside the type itself https://rakyll.org/generics-facilititators

Re: Go generics are not bad

#24

Post by zamalek » Fri, Jul 08, 2022, 11:24 PM UTC

saagarjha wrote: post #11

This is like the most cherry-picked example that could've been chosen. Java can't do this because the primitive types are not objects. Mentioning the performance of this is hilarious because 1. it's Daniel Lemire, he should know better and 2. the performance of pretty much every other thing that uses generics is terrible because of gcshapes being passed everywhere and 3. Java literally has a JIT to make generics fast…

> Java can't do this because the primitive types are not objects.

So this excuses the awful Java genetic how? "It smells like sewage in the basement because the basement is full of sewage." In addition, generics over primitive/stack/value types (including mathematical operators) is working just fine in the latest iteration of C#.

Re: Go generics are not bad

#25

Post by Quekid5 » Fri, Jul 08, 2022, 11:25 PM UTC

Thaxll wrote: post #15

saagarjha wrote: post #11

This is like the most cherry-picked example that could've been chosen. Java can't do this because the primitive types are not objects. Mentioning the performance of this is hilarious because 1. it's Daniel Lemire, he should know better and 2. the performance of pretty much every other thing that uses generics is terrible because of gcshapes being passed everywhere and 3. Java literally has a JIT to make generics fast…

How can Go does it even worse that Java where generics implementation is the worse of all modern language with type erasure. Java is way worse than Go on that aspect.

Type erasure is interesting. It turns out that not doing type erasure (combined with instanceOf-like things, like pattern matches on type parameters) breaks parametricity. Parametricity is a very powerful reasoning tool.

Of course, type erasure isn't the actual culprit in that case, but once you don't do it, it gets very tempting to allow pattern matching on type parameters...

Re: Go generics are not bad

#26

Post by zer0-c00l » Fri, Jul 08, 2022, 11:27 PM UTC

this article is hilarious:

1. go generics do this one thing 2. therefore they are good

Go generics are better than no generics but they're still limited, and that frustrates me.

Re: Go generics are not bad

#27

Post by [deleted] » Fri, Jul 08, 2022, 11:30 PM UTC

saagarjha wrote: post #11

This is like the most cherry-picked example that could've been chosen. Java can't do this because the primitive types are not objects. Mentioning the performance of this is hilarious because 1. it's Daniel Lemire, he should know better and 2. the performance of pretty much every other thing that uses generics is terrible because of gcshapes being passed everywhere and 3. Java literally has a JIT to make generics fast…

[deleted]

Re: Go generics are not bad

#28

Post by [deleted] » Fri, Jul 08, 2022, 11:30 PM UTC

zer0-c00l wrote: post #26

this article is hilarious: 1. go generics do this one thing 2. therefore they are good Go generics are better than no generics but they're still limited, and that frustrates me.

[deleted]

Re: Go generics are not bad

#29

Post by saagarjha » Fri, Jul 08, 2022, 11:30 PM UTC

zamalek wrote: post #24

saagarjha wrote: post #11

This is like the most cherry-picked example that could've been chosen. Java can't do this because the primitive types are not objects. Mentioning the performance of this is hilarious because 1. it's Daniel Lemire, he should know better and 2. the performance of pretty much every other thing that uses generics is terrible because of gcshapes being passed everywhere and 3. Java literally has a JIT to make generics fast…

> Java can't do this because the primitive types are not objects. So this excuses the awful Java genetic how? "It smells like sewage in the basement because the basement is full of sewage." In addition, generics over primitive/stack/value types (including mathematical operators) is working just fine in the latest iteration of C#.

It doesn't. Picking an area where Java is weak and where Go happens to be decent is the very definition of cherry picking. Go happens to do poorly in almost every other area and Java does meh in many (erasure, unsoundness, etc.) and excellent in others (profile-guided devirtualization).

Re: Go generics are not bad

#30

Post by moelf » Fri, Jul 08, 2022, 11:37 PM UTC

"not bad" is a weird bar to cross for a language that:

    1. decided generics is not needed
    2. went on for a decade
    3. implemented a version of it that is not performance-sensitive
    3.5. $$ by google