Hey everyone. We have arguments and return values for VCL custom subs now, I wrote a blog post about it to give a quick tour with a couple of examples.
The reference docs are here: Subroutines | Fastly Documentation
Hopefully this helps clean up VCL where you’re currently passing things around via headers, I’d love to see if you have situations where it helps make your VCL code more … normal.
Glad to answer any questions about using this, or about how we implemented it in the VCL compiler.