Re: [RFC] [Discussion] Bound-Erased Generic Types

> On May 12, 2026, at 3:07 pm, Seifeddine Gmati <azjezz@carthage.software> wrote: > > Hello Internals, > > I'd like to start the discussion on a new RFC adding bound-erased > generics types to PHP. > > Generic type parameters can be declared on classes, interfaces, > traits, functions, methods, closures, and arrow functions, with > bounds, defaults, and variance markers. Type parameters erase to their > bound at runtime; the pre-erasure form is preserved for Reflection and > consumed by static analyzers. > > - RFC: https://wiki.php.net/rfc/bound_erased_generic_types > - Implementation: https://github.com/php/php-src/pull/21969 > > Thanks, > Seifeddine. I think this is a good proposal and mirrors the various Python PEPs that added erased type hints in Python 3. Unlike TypeScript or Hack, Python has no official typechecker — though MyPy is a de facto standard, but it doesn’t ship alongside Python.. Those PEPs have spawned a healthy ecosystem of typecheckers (MyPy, Pyright, Pyre/Pyrefly, Pytype, ty, Zuban). Those typecheckers sometimes take different approaches to the same code (e.g. https://pyrefly.org/blog/container-inference-comparison/) but that seems healthy to me. I’ve been writing Hack for almost five years, and while it’s true that Hack ships with its own typechecker, I’ve also been able to build a new typechecker for Hack (only reusing the parser) in the span of about 6 months. When you don’t have to worry about docblock parsing a lot of things become quite a bit easier. This proposal would target a future version of PHP and would realistically only start to seep into code in 2027. I’m very confident that the average person writing PHP code in 2030 will prefer this proposal to using docblock types. Best wishes, Matt