minipicolisp pointers

[C K Kashyap]

Hi all,
Could I have some pointers on extending MiniPicoLisp to implement "call"
and external objects? My attempt at external object is here -
https://github.com/ckkashyap/pl/blob/bcf834075358e21abd4c7ec4adf6862e76df4348/miniPicoLisp/09012023/miniPicoLisp/src/main.c#L764
I am simply looking to avoid any known pitfalls in this area.
Regards,
Kashyap