Bye bye Prime

[Joe Horn]

(08-28-2014 08:55 PM)walter b Wrote:  Would "RPN features a finite stack with top level repetition and roll" be better to differentiate between RPN and RPL?

<opinion>

RPN and RPL are not mutually exclusive concepts. RPL is a Language that uses RPN Notation, just as FOCAL is a Language that uses RPN Notation. One universally recognized hallmark of RPN is adding 2 plus 3 to get 5 by executing 2 3 +. Both the HP-41 and the HP 50g do this, so they are both RPN machines according to that hallmark. The user interface is different, sure, but the Reverse Polish Notation is the same, so they are both RPN. RPN is not a user interface; it is a mathematical notation. RPN can be (and has been) implemented in many different user interfaces.

Many names have been proposed for these various implementations of RPN, but I don't think HP ever adopted any of those names officially, and none of them have really "stuck" in the user community. Until that happens, awkward things like "X-entry RPN" and "command-line 4-level RPN" and "infinite-stack RPN" and "Prime RPN" will need to be spelled out to avoid ambiguity.

We really, really, really need permanent, unambiguous, universally adopted NAMES for all these various RPN's. And PLEASE don't entertain the idea that any one of them is TRUE RPN. They ALL are "true RPN". Why? Because if you do 2 3 + to get 5, it's truly Reverse Polish Notation, so it's true RPN. The rest is details... details which hopefully some day can be clearly represented by meaningful, unambiguous, non-judgmental names for their respective RPN implementations.

</opinion>