PHP is a multi-paradigm, nominally typed, interpreted language.

Mostly known for powering large parts of the web, including Wikipedia, Etsy, Vimeo, and many other high traffic websites, it has over the last decade gained a relatively complete runtime checked type system supporting variance of union and intersection types, read only and asymmetric visibility modifiers for properties, and even some peculiar features such as typed class constants.

We’ll explore the history of PHP’s type system past, present, and future. How some design issues have been, or are in the process of being, fixed such as LSP bugs and inconsistent type juggling behavior. But also unfortunate design mistakes that the community is very reluctant of fixing due to the fundamental nature of them.

Gina Banyard has been a PHP Core developer since 2019 and is financed by The PHP Foundation since 2022. She used to actively maintain the PHP Documentation and be the lead translator for the French translation of it.

Previously she studied mathematics at Imperial College London with an emphasis on pure mathematics.

You can find her on Mastodon