6 ms·

I think the way Rust took with Generics should be the next step for Java, it for sure can boost the Java apps performance. In Rust you have both types erasure a

I think the way Rust took with Generics should be the next step for Java, it for sure can boost the Java apps performance. In Rust you have both types erasure and C++ style templates which don't erasure the types.

dep_b 6y ago
There is no next step for Java, because of backwards compatibility this is as good as it gets.
- Felk 6y ago
  While it does need to maintain backwards compatibility, Project Valhalla seems promising on improving on some of Java Generic's pain points. So it's not a dead end quite yet
kaba0 6y ago
I don’t think templates are wanted, but with the coming of unification of primitive and reference types, Java could get a huge speedup in performance.
- henryjcee 6y ago
  This has passed me by, what's happening?
  - BenoitP 6y ago
    Not so much a unification, as the new constructs sort of enhance and retrofit current primitives types. These new primitives are "class instances that lack object identity and can be stored and passed directly, without object headers or indirections". It will allow (almost) direct control over data layout. At least make it so that it is cache/prefetch/SIMD friendly. Here is the JEP: https://openjdk.java.net/jeps/401 https://openjdk.java.net/jeps/401
mrkeen 6y ago
> the way Rust took with Generics should be the next step for Java I have a List<Integer>. Maybe I want to replace List with something else, call it L. Can I write L<Integer> in Java? No. Rust? No. C#? No Kotlin? No. Does Go have generics yet? Once it does, I'm sure it'll be a No as well. Haskell and Scala got it right.
- riffraff 6y ago
  I don't understand what you're saying, what is the problem with L<Integer> ?
  - mrkeen 6y ago
    There shouldn't be a problem with it! <L> void process(final L<Integer> input) { } ------------------------------------------ <L> void process(final L<Integer> input) { ^ required: class found: type parameter L where L is a type-variable: L extends Object declared in method <L>process(<any>)
    - p2t2p 6y ago
      Works perfectly: public <T extends Collection<Integer>> T process(T collectionOfInteger) { return collectionOfInteger; }
      - petersellers 6y ago
        What if your "T" isn't a collection though?
        Joker_vD 6y ago
        Then what can you really do with it except of returning it back as-is?
        throw149102 6y ago
kasperni 6y ago
A Parametric VM [1] is part of Java's project Valhalla. However, it is currently some releases away. [1] https://cr.openjdk.java.net/~jrose/values/parametric-vm.pdf https://cr.openjdk.java.net/~jrose/values/parametric-vm.pdf
- _old_dude_ 6y ago
  Very cool, it seems to be the best of both worlds, the specialization of the class/fields is done the first time a specialized type is instantiated while the specialization of methods is done by the JIT. And the VM can specialize on any values, not just types.

dep_b 6y ago

There is no next step for Java, because of backwards compatibility this is as good as it gets.

Felk 6y ago
While it does need to maintain backwards compatibility, Project Valhalla seems promising on improving on some of Java Generic's pain points. So it's not a dead end quite yet

kaba0 6y ago

I don’t think templates are wanted, but with the coming of unification of primitive and reference types, Java could get a huge speedup in performance.

henryjcee 6y ago
This has passed me by, what's happening?
- BenoitP 6y ago
  Not so much a unification, as the new constructs sort of enhance and retrofit current primitives types. These new primitives are "class instances that lack object identity and can be stored and passed directly, without object headers or indirections". It will allow (almost) direct control over data layout. At least make it so that it is cache/prefetch/SIMD friendly. Here is the JEP: https://openjdk.java.net/jeps/401 https://openjdk.java.net/jeps/401

mrkeen 6y ago

> the way Rust took with Generics should be the next step for Java I have a List<Integer>. Maybe I want to replace List with something else, call it L. Can I write L<Integer> in Java? No. Rust? No. C#? No Kotlin? No. Does Go have generics yet? Once it does, I'm sure it'll be a No as well. Haskell and Scala got it right.

riffraff 6y ago
I don't understand what you're saying, what is the problem with L<Integer> ?
- mrkeen 6y ago
  There shouldn't be a problem with it! <L> void process(final L<Integer> input) { } ------------------------------------------ <L> void process(final L<Integer> input) { ^ required: class found: type parameter L where L is a type-variable: L extends Object declared in method <L>process(<any>)
  - p2t2p 6y ago
    Works perfectly: public <T extends Collection<Integer>> T process(T collectionOfInteger) { return collectionOfInteger; }
    - petersellers 6y ago
      What if your "T" isn't a collection though?
      - Joker_vD 6y ago
        Then what can you really do with it except of returning it back as-is?
        throw149102 6y ago

kasperni 6y ago

A Parametric VM [1] is part of Java's project Valhalla. However, it is currently some releases away. [1] https://cr.openjdk.java.net/~jrose/values/parametric-vm.pdf https://cr.openjdk.java.net/~jrose/values/parametric-vm.pdf

_old_dude_ 6y ago
Very cool, it seems to be the best of both worlds, the specialization of the class/fields is done the first time a specialized type is instantiated while the specialization of methods is done by the JIT. And the VM can specialize on any values, not just types.