HP Forum Archive 21

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aOT--RPN Computer Languages Message #1 Posted by Matt Agajanian on 10 May 2012, 11:23 p.m. 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?

Re: aOT--RPN Computer Languages Message #2 Posted by Paul Dale on 10 May 2012, 11:39 p.m., in response to message #1 by Matt Agajanian 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

Re: aOT--RPN Computer Languages Message #3 Posted by Marcel Samek on 10 May 2012, 11:44 p.m., in response to message #1 by Matt Agajanian LISP does not use postfix syntax. Its expressions use prefix syntax. M.

Re: aOT--RPN Computer Languages Message #4 Posted by Matt Agajanian on 10 May 2012, 11:58 p.m., in response to message #3 by Marcel Samek 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.

Re: aOT--RPN Computer Languages Message #5 Posted by Eric Smith on 11 May 2012, 12:27 a.m., in response to message #4 by Matt Agajanian Quote: 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".

Re: aOT--RPN Computer Languages Message #6 Posted by Walter B on 11 May 2012, 12:32 a.m., in response to message #4 by Matt Agajanian I concur with Valentin who called it RePeLling for obvious reasons.

Re: aOT--RPN Computer Languages Message #7 Posted by Nick_S on 11 May 2012, 7:16 a.m., in response to message #1 by Matt Agajanian A Web search on concatenative programming languages will reveal a few more stack-based languages, e.g., Joy, Cat and Factor. Nick

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