On Tue, Sep 20, 2022 at 4:16 PM Thomas Munro <thomas.munro@gmail.com> wrote:
> To explain my earlier guess: reader code for #S(STRUCTNAME ...) can
> bee seen here, though it's being lexed as "PLAN_SYM" so perhaps the
> author of that C already didn't know that was a general syntax for
> Lisp structs. (Example: at a Lisp prompt, if you write (defstruct foo
> x y z) then (make-foo :x 1 :y 2 :z 3), the resulting object will be
> printed as #S(FOO :x 1 :y 2 :z 3), so I'm guessing that the POSTGRES
> Lisp code, which sadly (for me) was ripped out before even that repo
> IIUC, must have used defstruct-based plans.)
That defstruct guess is confirmed by page 36 and nearby of
https://dsf.berkeley.edu/papers/UCB-MS-zfong.pdf.