I’m a “Neovim Refugee” trying to get a deeper/better understanding of how emacs lisp works and how i can use it to expand on my emacs setup. I have never done anything in lisp before and still struggle to understand how single quotes signify a function or what ever.
With that said, i was also planning on doing AoC this year. Originally i wanted to look into zig or go, but now think that this might be the opportunity to dive into lisp for a bit.
But with knowing basically nothing: Is this even “viable”, or advisable? Should i be looking at common lisp instead? Or would you say that’s a pretty dumb idea and i should rather learn it in a different way?
Is this even “viable”, or advisable? Should i be looking at common lisp instead? Or would you say that’s a pretty dumb idea and i should rather learn it in a different way?
You could have just tried any of previous years of AOC. Just go to their webpage and start doing them.
You can do them in both elisp or cl or any other programming language, including bf. I think elisp works rather well for AOC, but it will really depend on your skills.
You can look on their reddit and see if you can find elisp solutions from previous years to see if anyone has done some AOC challanges in elisp.
How you will learn elisp depends on you. If you are discussing about learning it, you ain’t learning it, you are discussing. Programming is very similar to learning a new language, playing music or learning any other new skill. Just go and do anything, and you will learn something.
You could have just tried any of previous years of AOC. Just go to their webpage and start doing them.
I did just that, to see how “viable” Elisp would be. I solved this: https://adventofcode.com/2022/day/1
with:
(cl-labels
((split-to-numbers (lst)
(--map (->> (s-split "\n" it) (-map #'string-to-number)) lst)))
(skip-chars-forward " \t\n")
(let* ((input (buffer-substring-no-properties (point) (point-max)))
(subs (->> input s-trim (s-split "\n\n") split-to-numbers))
(sorted (cl-sort (-map #'-sum subs) #'>)))
(message "Winner: %s" (car sorted))))
and then with:
(save-excursion
(calc-pop (calc-stack-size))
(while (progn (skip-chars-forward " \t\n") (not (eobp)))
(save-selected-window
(calc-grab-region (point) (progn (forward-paragraph) (point)) nil)
(calc-eval "VR+" 'macro)))
(calc-pack (calc-stack-size))
(calc-vector-max nil)
(calc-top-n 1))
which turned out to be ~1000 times slower, but also worked.
So u/domsch1988, it’s demonstrably doable in Elisp :)
the quote is arguably the most important part of lisp as it allows symbolic processing (without that macros and eval wouldn’t be a thing I reckon).
I’ll try to provide a weird explanation. Consider this:
five = 4
So is this a four or a five? The value is four but it’s assigned to a symbol “five”. When dealing with values, “five + five” will be 8. However, what if I don’t care about the values (at least yet)? then I’ll be manipulating the expression in terms of the elements (symbols) themselves and not what they signify (values). At that level, we don’t even know what + means. You assume it’s a math operation because of the semantics you’ve been taught. for all we know it may be something else entirely, like a variable (did you know that some languages allow you to use chinese glyphs or norse runes for variables?).
So quote operator tells lisp that you don’t want the “thing” to be evaluated into the value behind it. (quote five) isn’t “4”, it’s literally the symbol “five”. (quote (+ 1 2 3)) isn’t 6, it’s a list of +, 1, 2, and 3. You can eval that list so lisp executes it: (eval (quote (+ 1 2 3)). Also consider: (quote (1 + 2)) is perfectly fine, it’s just a list, but you can’t evaluate it as lisp doesn’t have a function or operator named 1 (although you may be able to define it yourself)
It was a bit of a weird explanation but i hope it helps
This
I tried it a couple years ago and recall that there were others. Lots of fun and good way to learn.
Everybody learns differently, and there’s a lot of people who learn languages through advent of code. AoC can have some problems that could take literal years to solve with a naive solution, so just keep in mind you can cancel a slow function with C-g and you don’t need to reboot emacs entirely.
The other thing to keep in mind is that this would help you learn elisp (and general lisp syntax), but won’t teach you as much about the functionality you can do with emacs. It’s still a good place to start though, since you’ll need to know elisp to customize emacs.
Lastly I would recommend looking into Structural Editing a bit, here’s a decent article that covers the basics in vanilla emacs. This is by no means a requirement for writing elisp, but using the sexp commands makes working with all the parentheses infinitely easier.
Good luck!
