PHP: rfc:bound_erased_generic_types

This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong.
====== PHP RFC: Bound-Erased Generic Types ======
  * Version: 0.1
  * Date: 2026-05-06
  * Author: Seifeddine Gmati, azjezz@carthage.software
  * Status: Draft

===== Introduction =====

This RFC proposes adding generic type syntax to PHP. Type parameters declared on classes, interfaces, traits, functions, methods, closures, and arrow functions are erased to their declared bounds at compile time: the runtime enforces the bound, while parametricity is verified by static analysis tools. Type information that today lives in ''@template'' and ''@param Container<int>'' docblocks becomes first-class language syntax, exposed through a new Reflection API.

<PHP>
<?php

final readonly class Box<+T: mixed> {
    public function __construct(
      public T $value,
    ) {}

    public function zip<O>(O $value): self<Pair<T, O>> {
        return new self(new Pair($this->value, $value));
    }
}

function first<T>(array<T> $items): ?T {
    return $items[0] ?? null;
}

$box = new Box::<string>("hello, world");
</PHP>

===== Proposal =====
TBD.

==== Examples ====
TBD.

===== Backward Incompatible Changes =====
TBD.

===== Proposed PHP Version(s) =====
Next PHP 8.x.

===== RFC Impact =====
==== To the Ecosystem ====
TBD.

==== To Existing Extensions ====
TBD.

==== To SAPIs ====
TBD.

===== Open Issues =====
None at this time.

===== Future Scope =====
TBD.

===== Voting Choices =====
TBD.

===== Patches and Tests =====
TBD.

===== Implementation =====
TBD.

===== References =====
TBD.

===== Rejected Features =====
None at this time.

===== Changelog =====
  * 2026-05-06: Initial draft.
Page Tools
