[mmphosis]

I prefer infix over prefix. And don't forget postfix

    x 3 1 2 x * + - %

I definitely prefer white-space over commas and other syntactic obstacle courses.

[Tyr42]

I mean I would probably punch that in as

    x 2 * 1 + (-) 3 + x %

When I was using my rpn calculator. (-) flips the sign of the number on top of the stack.

Or use flip -. But you can avoid growing the stack long enough to be confusing.