aOT--RPN Computer Languages


Hello all.

Am I right in saying that FORTH is a postfix-structured language? Also, is LISP? Aside from these, are there other postfix-basd computer languages still in use?


Postscript is in very widespread use. Many, many, many, many printers use it as their native page description language. Of course, not many people see it but it is there and can be programmed in.

Quite a lot of interpreted languages use small stack machines for their intermediate code but these only marginally count as computer languages.

- Pauli


LISP does not use postfix syntax. Its expressions use prefix syntax.



Thanks for the clarification. I'm not certain where on when I came across it but, I though that the RPL that is implemented in HP-28 and 48 series stood for Reverse Polish LISP. So, I thought LISP was a postfix-based notation. Or is it that the 28/48 series use LISP but a with Reverse Polish command structure?

Edited: 10 May 2012, 11:58 p.m.


Or is it that the 28/48 series use LISP but a with Reverse Polish command structure?

RPL is Lisp-like in some respects, but it definitely is not Lisp, and it obviously uses Reverse Polish Notation.

Note that "RPL" doesn't officially stand for anything. Bill Wickes has stated that the developers never called it anything other than "RPL". There are several unofficial expansions, including "ROM-based Procedural Language".


I concur with Valentin who called it RePeLling for obvious reasons.


A Web search on concatenative programming languages will reveal a few more stack-based languages, e.g., Joy, Cat and Factor.


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