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_old_dude_

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_old_dude_
·22 日前·議論
For me, the difference is that if methods are inlined, the compiler is still required to do a copy for structs but not for value classes.

I do not know how this is called.
_old_dude_
·22 日前·議論
I think pass by copy is a consequence of being modifiable.

The other solution is to stack allocate and pass a pointer but as i said, unlike in C#, i do not think it's possible to do that in Java.

In Go, you can stack allocate but when you send a pointer (that escapes), the compiler will heap allocate the object.
_old_dude_
·22 日前·議論
The article has a section about that.

For me, a struct in C/C# can be modified and is passed by copy while a value class can not be modified and is passed by value.

I do not think you can do stack allocation in Java.
_old_dude_
·27 日前·議論
The usual GC tradeoff is between memory and CPU performance. If you set the memory max high, the GC will run less often, you get less pause time.

So I do not understand why it's a surprise that minimizing the pause time requires more memory. Is it because there is no knob to set either the max pause time or the max memory ?
_old_dude_
·先月·議論
I agree. And the next section is very clear that they want to kill the project.

  > For example, rather than proposing one single concrete JIT implementation,
  > it may make more sense for the PEP to describe a JIT infrastructure that
  > can support multiple implementation strategies.
  > Since many different and promising JIT tracing approaches continue to be proposed,
  > we believe the infrastructure should make it easy to experiment with and evaluate
  > those approaches within CPython rather than be highly coupled with a single strategy.
Allowing multiple strategies is far harder and as far as I know, JIT tracing is still unproven.
_old_dude_
·先月·議論
You need more than that for the example with setTimeout(). It requires to be able to freeze the stack and then go back later.

You need stackful coroutine (like goroutine) for that.
_old_dude_
·2 か月前·議論
If you do not block 3rd party harness, people will discover that a good harness is more important than a good model.
_old_dude_
·2 か月前·議論
Yes, and let's not forget Stephen Elop's 'Burning Platform' Memo

https://www.wsj.com/articles/BL-TEB-2031
_old_dude_
·3 か月前·議論
Parser generators are great in Python (Lark for me) so you can iterate fast and get a runtime spec of your grammar.

A hand-written recursive descent parser is something you do later when you start to industrialize your code, to get better error messages, make the parser incremental, etc.

Bison/ANTLR are code generators, they do not fit well in that model.
_old_dude_
·3 か月前·議論
In C#, all instances have a class, so there is already a discriminant, the class itself.

In the article, the example with the switch works because it switches on the class of the instance.
_old_dude_
·7 か月前·議論
In Scala 3, the inline keyword is part of the macro system.

When inline is used on a parameter, it instructs the compiler to inline the expression at the call site. If the expression is substantial, this creates considerable work for the JIT compiler.

Requesting inlining at the compiler level (as opposed to letting the JIT handle it) is risky unless you can guarantee that a later compiler phase will simplify the inlined code.

There's an important behavioral difference between Scala 2 and 3: in 2, @inline was merely a suggestion to the compiler, whereas in 3, the compiler unconditionally applies the inline keyword. Consequently, directly replacing @inline with inline when migrating from 2 to 3 is a mistake.
_old_dude_
·8 か月前·議論
There is a modern equivalent based on Linux criu.

https://github.com/CRaC/
_old_dude_
·8 か月前·議論
Yes, the version in Java is clearly less elegant. Java has map+lambda and compareTo (<=>) but no tuple assignemnt and no splat.

    record AppVersion(int major, int minor, int patch) implements Comparable<AppVersion> {
      public static AppVersion of(String version) {
        var array = Arrays.copyOf(Arrays.stream(version.split("\\.")).mapToInt(Integer::parseInt).toArray(), 3);
        return new AppVersion(array[0], array[1], array[2]);
      }

      public int compareTo(AppVersion other) {
        return Comparator.comparingInt(AppVersion::major)
            .thenComparingInt(AppVersion::minor)
            .thenComparingInt(AppVersion::patch)
            .compare(this, other);
      }

      public String toString() {
        return "%d.%d.%d".formatted(major, minor, patch);
      }
    }