I use hp48 app on the iPhone.

Obviously it does not have the tactile feedback of the original. But it’s a far cry from using on a desktop with a mouse.

Using a REPL as a replacement does not mimic the experience, I don’t think. Not for me at least.

Mind, I’m talking a generic REPL. Like a CL REPL or similar, obviously not some custom calculator REPL.

First off, you’re missing the stack, which is significant. CL can almost mimic this with , *, and *. But while it provides a free, handy value store, it’s not the same. You’d end up with contrivances like:

  (* * **)

So, for me, a calculator and its hand held form factor, especially something like the high end HPs, go hand in hand.

No doubt someone could (and likely has) code up a dedicated calculating experience, but a generic REPL I find to be unsuccessful in that role.

If you want to use a REPL as a pleasant calculator you really want an APL-family language or a modern concatenative language like Factor. Sexprs are horrendously verbose in comparison.

‘dc’ has been a thing on Unix forever. It uses RPN, provides arbitrary precision arithmetic, and is programmable.

https://en.wikipedia.org/wiki/Dc_%28computer_program%29