I wanted to do some statistics, so I accidentally learned J (thinking it was R). J is like APL, but with digraphs (multiple characters) instead of special characters as symbols.
I don't think I ever actually did any stats with J, but I did play with it for a long time.
J is like an old school text adventure where you start with a blank screen that reads "You are in the woods" and, before you know it, it's Monday morning and you're considering calling out of work because you've almost decoded some elvish runes you found on a rock.
R is the single player campaign of a modern first person shooter, where you have infinite lives and your health regenerates if you sit and think for a while.
This isn't a perfect analogy. Maybe J is high school Spanish class, and R is Google translate? I remember enjoying J as a language and R as a tool. It's exciting to express new things in J. It's easy to do familiar things in R.
R also is really well documented - there was a time where experts were asking basic questions on Stack Overflow and answering them themselves, because that's where people look for documentation.
I've been trying to improve my J skills by doing the https://adventofcode.com/2022 puzzles. I got stuck on day 7 because recursion in J is possible but an advanced level incantation.
Day 1 was five short lines of code for Part One and another two lines for Part Two.
Each line of code needed four or five long lines of documentation.
On the J website the first sentence is:
'J is a high-level, general-purpose programming language that is particularly suited to the mathematical, statistical, and logical analysis of data.'
So I can see him thinking he has the correct language.
Math student Ken Iverson being annoyed at the inconsistency of math notation and its precedence rules decided to come up with a better one. "Iverson notation" or "the notation", he went through Harvard and became Dr Iverson, got picked up by Adin Falkoff at IBM when they were designing the IBM/360 processor and adapted the notation for the blueprints of how the thing would work, and then got rid of superscripts and subscripts and cut it down a little so it could become a line-based executable thing to run on an IBM/360 as a kind of matrix-aware desktop calculator / "A Programming Language" (APL). IBM made custom Selectric/golf-ball printer heads and keyboard overlays for it.
An APL keyboard typically wasn't exactly a custom keyboard, but a standard keyboard with APL characters accessible through modifier keys. Often there were adhesive labels on the front of each key showing the special characters or you could get custom keycaps that had the special characters printed on the front. And of course many of the special characters were created through overstrike rather than separate keys. Way back, I programmed in APL on a DECWriter that had support for APL characters.
I have a keycaps set imitating the classic Space Cadet keyboard (from Symbolics Lisp workstations). The Space Cadet had APL tops and fronts [1], but these caps only have the tops presumably because the cost to get keycaps printed on the fronts would be way too high. Frustrating though. I've thought about getting the rest printed on clear plastic adhesive.
