Move IntFunction to scala and don't allow throwing

[mdedetrich]

In #2198 we defined an IntFunction but there were some issues with the definition

• There is no reason for IntFunction to allow throwing, this is used in retry functions for the delayFunction and supplying a function that can throw makes no sense and can lead to undefined behaviour
• Moves implementation to scala since thats where all of the other functions sit, there is no reason to pointlessly split our implementations in java and scala, and having it sit in Scala is beneficial if we want to explore native/js. Java users can still use these functions without any problems (it in fact creates the exact same bytecode)

[He-Pin]

? what's the poin of this?

[mdedetrich]

We already have a place where we define all of our functional interfaces, its in actor/src/main/scala/org/apache/pekko/japi/function/Function.scala. In your PR you created another implementation in Java which means we have functional interfaces defined in both Scala and Java for no good reason.

Lets keep all of the functional interfaces defined where they already are in actor/src/main/scala/org/apache/pekko/japi/function/Function.scala so its consistent.

[He-Pin]

The reason is in #2185, ok?
Even Akka-sdk is now Java-first.

[He-Pin]

These are Java APIs, so shouldn't they be written in Java? Just because they were done in the past doesn't mean they should be done now.

[mdedetrich]

The reason is in #2185, ok? Even Akka-sdk is now Java-first.

If you are going to make a decision like move everything to Java (or to Scala) for that matter, you need to discuss it with community first. You can't just sneak it into PR's because you think its a good idea.

Please discuss this with community first, also whether to throw an exception or not is a separate matter from whether functions can throw exceptions.

[He-Pin]

Check #2185 first

And then why can't the IntFunction throw? Are you kidding me?

Then tell why an Array(index: Int) can throw IOBE`?

[mdedetrich]

Check #2185 first

And then why can't the IntFunction throw? Are you kidding me?

Then tell why an Array(index: Int) can throw IOBE`?

Its not that Int functions can never throw, its that throwing an exception as a supplier function in a pekko stream doesn't make any sense.

[He-Pin]

These are common functions. Thanks. Do you actually write Java on a daily basis? How much Java do you write on a daily basis?

[He-Pin]

And you should never define such a method in Scala , there is already one, In java's stdlib.

[mdedetrich]

And you should never define such a method in Scala , there is already one, In java's stdlib.

Then we should use that one, I will change the PR to do so.

These are common functions. Thanks. Do you actually write Java on a daily basis? How much Java do you write on a daily basis?

I write Java/Kotlin frequently, and there is a reason why the Java functional interfaces do not allow exception throwing (albeit they should have also provided alternatives that do allow throwing)

[He-Pin]

There is already a Java's IntFunction in stdlib

[mdedetrich]

There is already a Java's IntFunction in stdlib

Fixed and pushed

[pjfanning]

lgtm - I'm ok with this if @He-Pin is happy with this change

[He-Pin]

actually we should just do a revert instead of this.

[He-Pin]

lgtm

[He-Pin]

Although this is not the result I want, I can accept it, reduce the change set help anyway.