There are some notes on PHP RFCs, why some were declined, and what others might need for them to be implemented.
The purpose of these documents is to avoid information from being lost and to try to avoid conversations needing to be repeated multiple times on PHP internals.
Auto-capture closure aka multi-line blocks
Call site error or exception control
Strict mode and internal engine callbacks
Tuple return declarations. Hmm I wrote this one up twice as multiple return type
These need to be summarised.
packages.md partial_function_application.md
PHP is actually getting better. These are all things that used to be pipe-dreams, but are now in PHP core.
Enums implemented by Enumerations.
Immutables - this is done through the Readonly properties. There is still some work to do here, as currently it is slightly annoying to clone an object and during the clone change some of it's properties.
Null short-circuiting - https://wiki.php.net/rfc/nullsafe_operator
Referencing functions - implemented by First-class callable syntax
PHP is actually getting better, but that means that some solutions to problems have become pretty moot, as they seek to solve problems that are now less of a problem.
Please read the contributing guidelines before writing your 4,000 word novella on why some RFC really should pass.
I reserve the right to be as opinionated as I feel like when commenting on RFCs; I'm not going to attempt to stay 100% neutral when talking about RFCs that I consider to be either dumb or bad for PHP.