"you've been stacked"

-- HP calc owner

Last year I finally read the whole manual (as a teen I only used the symbolic differentiator, most useful and magical to my brain at the time). Since I learned about Lisp, so RPN programming features appealed to me. I realized that:

1) RPN has lambda << 2 + >> means (lambda (...) (+ 2 ...))

2) RPN has a short syntax for them << a -> a 2 + >>

Yes, 1990 HP RPN had arrow notation out of the box. Take that ES6 !

> 2) RPN has a short syntax for them << a -> a 2 + >>

The syntax is slightly different. What it should be is this

<< -> a << a 2 + >> >>

The arrow introduces a binding form that captures the top n levels of the stack into n named local variables. (There's also a lower level implementation that forgoes the names in favor of a lookup-by-ordinal scheme that's a lot faster.)

The other notable difference from what you might expect is that the lexical environment is not captured:

Consider this function:

<< -> a << << a 2 + >> >> >>

What it returns is a function object that looks like this, except that 'a' is a local variable reference rather than the global variable reference it looks like:

<< a 2 + >>

Evaluating this results in an error, because while 'a' is represented as a local variable reference, the environment containing the local binding for 'a' is no longer available.

You're totally right. I already forgot the deails.

I just put out my hp49.. god how I love these things.

ps: I just found out the latest attempt I did last years was a var called REC = << -> U << U U EVAL >> >> .. pretty sure I was trying a fixpoint CPS factorial in RPN

HP48(S(X)) also came with two excellent manuals with hundreds of pages of documentation. My only regret is that when I was in college, I could have written better programs. I tended to write huge functions with a deep stack, hard to understand, debug and modify. Had I know what I know now, I would have written dozen of small function and relying more in lambdas... And I didn't know I can use named arguments.

at least you did write them, I have respect for people suffering complexity when they don't know better

If you're enjoying that, you'll find even more connections with Forth, also a very cool programming language.

https://en.wikipedia.org/wiki/Forth_(programming_language)

I love stack languages. Forth, Factor, Joy, Cat .. (all the concatenative crew).

ps: there are some Chuck Moore talks on youtube that are worth gold. His CPUs are heaven

Can you please give links for those of his videos that you liked?

My bad, my favorite wasn't on youtube, but infoq (thanks to them) https://www.infoq.com/presentations/power-144-chip

then https://www.youtube.com/results?search_query=chuck+moore+ga1...

https://www.youtube.com/watch?v=odBjuSCX8jE

and Kalny's videos https://www.youtube.com/watch?v=KSTjQA-iz4w

Saw the links you posted, thank you.

You're welcome. Enjoy.

Have you used his greenarrays chips? If so I'd love to hear anything you have to say on them and your Forth experience in general.

oh no, I was far removed from this kind of things, I'm a java/python coder let's say. But I recently dug into low level electronics so I hope I can put my hands on one.

Same. I've only done microcontrollers/asm in college.

At my last job, which involved a lot of number work, my boss would often pick up my HP-12C to quickly calculate something we were talking about. Every single time, he'd say, "Your calculator is broken," then put it back on my desk. It became a running joke of ours.

A 42S that a high school friend had was how I first learned about RPN and HP calculators. Bought a 48G soon after which I still have. I use the prime app on android now which works well when needed.