On Mon, May 18, 2026, at 3:33 AM, Seifeddine Gmati wrote:
> The `~~Type` proposal raises two questions I don't see clean answers to:
>
> 1. *Lexical grammar inside `~~`?* Whitespace breaks conditional types
> (`$var is Foo ? A : B`). `$` breaks variable-using expressions. `{`
> breaks array shapes. `<` breaks generics. Every plausible stopping rule
> breaks a class of type expressions SA tools currently support.
>
> 2. *AST shape?* Either an opaque string (tools still parse it
> themselves, still disagree, gain over docblocks is just location) or
> structured (PHP has committed to an AST for type expressions it doesn't
> enforce, which is the architectural pattern you wanted to avoid).
>
> The speed advantage of docblocks comes from PHP not parsing them at
> all. Moving syntax into the language reduces that velocity regardless
> of whether PHP enforces semantics. The RFC's trade-off is to move the
> *enforceable* parts into the standard and leave the *innovation* parts
> in docblocks. Future RFCs will incrementally move what's stable enough
> to standardize, the docblock channel stays open for fast iteration.
Rowan's "erased user-extensible type system" is an interesting idea, and I
think it's worth exploring. But I don't think this RFC is the place for it.
This is a partially-enforced-generics proposal, so using an "ignored by the
engine" flag for its syntax would make things more confusing, not less.
I'd rather move the discussion of a user-extensible type system to its own
discussion. I don't think it's necessary for generics, which are already
extensible in a well-defined and industry-standard way.
--Larry Garfield
