Hi Tim,
Great questions, I’ll try to answer them all.
Sorry for the late answer, looked like there are no interest in the RFC and I almost forgot about it.
> On Jun 4, 2025, at 12:23 PM, Tim Düsterhus <tim@bastelstu.be> wrote:
>
> In the implementation I'm seeing that `$a = function() => 123;` will also become legal (“short closures with function instead of fn”). This is not mentioned in the RFC text. It also raises the question how that variant will interact with variable capturing.
Nope. Anonymous functions won’t become available. Use arrow functions with auto-capturing instead.
RFC propose classic function and class methods become available be one-liners
> An AST printing test in the implementation would be useful to have. You can do that with `assert(false && new class { });` (using an anonymous class).
Sure, when RFC successfully pass Voting stage, alright?
> I believe the reasoning given is not a fair comparison. The RFC says that `getName() "Name"` would be the relevant information, which I can agree with. But this is not what the proposed syntax looks like. A fair comparison would be:
>
> function getName() { return "Name"; }
> function getName() => "Name";
>
> And when compared like this, it becomes clear that you are trading `{}` for `=>` and effectively only save the `return`, which to me provides little incremental value. Especially when comparing the signatures from the Calculator example:
>
> public function multiply(int $a, int $b): int => $a * $b;
> public function multiply(int $a, int $b): int { return $a * $b; }
Cool point. I’ve updated examples.
> I also don't like how the actual implementation is pushed to the right of the line. This makes it harder for me to scan for it. The linebreaks that the RFC states “create cognitive overhead” guide the eye for me. So perhaps we should also compare:
>
> public function multiply(int $a, int $b): int
> => $a * $b;
> public function multiply(int $a, int $b): int {
> return $a * $b;
> }
I don’t think it’s correct comparison. Why the linebreak should be there?
If it is set by an editor, it’s not programmer/language issue. Set your editor to:
- Single expression function becomes regular when the line is greater than 180 chars AND/OR Vice-versa
- Same above, but ignore instead of breaking the line
- Other
> So basically the only thing we gain is the removal of a keyword in some situations. When trying to extend the logic in a function to more than one expression (which is not unlikely for methods), I would be forced to make multiple “boilerplate” changes instead of just adding my logic, effectively undoing any benefit the syntax might've provided.
Correct point, almost. Intellij IDEA provides quick action for Kotlin SEF’s, so you may turn SEF -> Regular and vice-versa calling CTRL+ENTER, Chose correct option, Enter.
Usually, we read code tens times often then write.
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Best regards,
Dmitrii Derepko.
@xepozz
