I recall Real3D, a DCC app originating from the Amiga and ported to Windows NT in the 90's. It allowed plug-ins to be written in RPL (Real Programming Language)

I recall Real3D, a DCC app originating from the Amiga and ported to Windows NT in the 90's. It allowed plug-ins to be written in RPL (Real Programming Language) a Forth dialect. I wrote a 5k line RenderMan RIB exporter for this app in RPL. I remember how hard this seemed when I started but how natural working in a RPN language felt after only a few hours. It was almost as if the stack had become an extension of my brain. Trivia: Real3D was eventually rewritten from scratch and is now called Realsoft 3D. Afaik it doesn't support RPL/Forth any more.