Comment by Someone

Postfix doesn’t need parentheses.

Prefix technically doesn’t need, either, if you avoid functions taking variable number of arguments and have a grammar that can reliably detect function calls (could be hard if you’re allowing higher-order functions)

Even with functions taking a variable number of arguments, you could do it the C way and use the argc, argv trick, giving you

  * 2 + 3 5 6 7 3  ⇒  (* (+ 5 6 7) 3)  ⇒  54

I think you’d have to be a bit of a masochist to do that, though.

That also is why I think varargs functions tend to be rare in bare bones forths. You’d have to write

  5 6 7 3 + 3 2 *

Using custom names for the varargs functions would help for the 2-argument version.