[External] : Re: Record pattern and side effects

[forax at univ-mlv.fr]

> From: "Brian Goetz" <brian.goetz at oracle.com>
> To: "Remi Forax" <forax at univ-mlv.fr>
> Cc: "amber-spec-experts" <amber-spec-experts at openjdk.java.net>
> Sent: Friday, May 6, 2022 3:11:43 PM
> Subject: Re: [External] : Re: Record pattern and side effects

>> The accessor throws an exception and with the semantics you propose it will
>> happily be wrapped by as many MatchExceptions as possible.

> But this class is already so deeply questionable, because accessors should not
> throw exceptions, that we've lost the game before we started. Whether the
> exception comes wrapped or not is like asking "do you want whipped cream on
> your mud and axle-grease pie" :)
People makes mistakes and other ones have to debug it. 

> (Also, I don't see where the exception is wrapped multiple times? So I'm not
> even sure you are clear on what is being propsed.)
"I don't see" -> that's exactly my point ! Nobody will see it. 

Rémi 

>> public sealed interface RecChain {
>> default int size() {
>> return switch (this) {
>> case Nil __ -> 0;
>> case Cons(var v, var s, var next) -> 1 + next.size();
>> };
>> }

>> record Nil() implements RecChain { }

>> record Cons(int value, int size, RecChain next) implements RecChain {
>> @Override
>> public int size() {
>> return size != -1? size: RecChain.super.size();
>> }
>> }

>> public static void main(String[] args){
>> RecChain chain = new Nil();
>> for (var i = 0; i < 100; i++) {
>> chain = new Cons(i, -1, chain);
>> }
>> System.out.println(chain.size());
>> }
>> }

>> Rémi
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