On Tue, 17 Jan 2023 10:11:49 GMT, Rémi Forax <fo...@openjdk.org> wrote:
>> src/java.base/share/classes/java/lang/invoke/MethodHandles.java line 6754:
>>
>>> 6752: filter(t -> t.parameterCount() > skipSize).
>>> 6753: map(MethodType::ptypes).
>>> 6754: reduce((p, q) -> p.length >= q.length ? p :
>>> q).orElse(EMPTY);
>>
>> Could avoid the need to introduce `EMPTY` if you make the stream expression
>> return the longest list directly:
>>
>> reduce((p, q) -> {
>> var longest = (p.size() >= q.size()) ? p : q;
>> return List.of(Arrays.copyOfRange(longest, skipSize,
>> longest.size()); // checking isEmpty() is redundant here since we filter on
>> `t.parameterCount() > skipSize`
>> }).orElse(List.of());
>
> Using lambdas inside MethodHandles is quite dangerous given that lambdas are
> initialized using method handles. It may work now because
> longuestParameterList() is not called when initializing a lambda but it may
> make any changes in the implementation of lambdas painfull in the future.
Precious little method handle use in lambda bootstrap since JDK 11. Though I
agree with the sentiment - having fixed a number of bootstrap issues in the
past - `MethodHandles` is a small step up the abstraction ladder and the code
in particular already uses a number of method refs and lambdas.
-------------
PR: https://git.openjdk.org/jdk/pull/12025
