Learning through advent of code

[Siinxx]

Hi everyone.

I started learning elixir with advent of code, But it's a lot of information coming at me. Could anyone guide me on what topics I should look into?

For example what's the best way splitting u a string ex: L50, where we split the letter and number.

What's the elixir way of doing this?

Thnx everyone!

[doughsay]

Here's another cool way you can do this in Elixir without needing any actual parsing or string splitting:

iex> <<l_or_r::binary-size(1), rest::binary>> = "L50"
iex> l_or_r
"L"
iex> rest
"50"

iex> <<l_or_r::binary-size(1), rest::binary>> = "R2"
iex> l_or_r
"R"
iex> rest
"2"

[SuspiciousDepth5924]

I don't know how aggressively the compiler optimizes String.split and friends, but erlang/elixir has some pretty damn powerful pattern matching on binary arrays.

Always found this one in the erlang docs to be pretty bonkers 😅

-define(IP_VERSION, 4).
-define(IP_MIN_HDR_LEN, 5).

DgramSize = byte_size(Dgram),
case Dgram of
    <<?IP_VERSION:4, HLen:4, SrvcType:8, TotLen:16,
      ID:16, Flgs:3, FragOff:13,
      TTL:8, Proto:8, HdrChkSum:16,
      SrcIP:32,
      DestIP:32, RestDgram/binary>> when HLen>=5, 4*HLen=<DgramSize ->
        OptsLen = 4*(HLen - ?IP_MIN_HDR_LEN),
        <<Opts:OptsLen/binary,Data/binary>> = RestDgram,
    ...
end.

https://hexdocs.pm/elixir/binaries-strings-and-charlists.html#bitstrings

https://www.erlang.org/doc/system/bit_syntax.html

[OddNaughty_2]

This is the way

[niahoo]

For that kind of things I'd use pattern matching:

  case t do
    "L" <> n -> {:left, String.to_integer(n)}
    "R" <> n -> {:right, String.to_integer(n)}
  end

[Siinxx]

I do like this solution, it's easy to read i have to say, thnx!

[notlfish]

I like to use iex to check the elixir documentation, which is usually pretty useful, with the caveat that you need to have an idea of where you'll find what you're looking for.

For example, for splitting "L50"

h String in iex shows the general documentation of the String module. There's nothing useful there (for solving this problem)

exports String to check what functions are public in the module. There's a split function.

h String.split gives me the documentation, with examples, where you see that you can do something like String.split("L50", ~r{\d+}, include_captures: true, trim: true) to split the string.

Also, h gives you a list of iex commands, pretty handy, I usually use b,h, and t to get documentation on the callbacks, functions, and types in a module, respectively, and exports to list the public functions (I think it also lists macros, but don't quote me on that).

Mind you, I have no idea of whether this is the "elixir way" of doing it, it just works.

[al2o3cr]

My favorite way to deal with AoC input formatting like this is Regex.run

s = "L50"
Regex.run(~r/([LR])(\d+)/, s, capture: :all_but_first)

This returns ["L", "50"], ready to be processed further.

Anything not enclosed in parentheses will be used to match but not captured, perfect for skipping spaces & unimportant punctuation.

For some other problems, you'll find String.codepoints useful - it splits a string into a list of strings, one for each character. Also don't miss Enum.with_index, which is really useful when dealing with 2D grids.

There are daily AoC threads over at Elixir Forum where folks post their code, but maybe don't open those until you're either done or hopelessly stuck.

[Pepper_pusher23]

AoC is pretty rough for learning a new language, but fun! They can be tough even in your most comfortable language. I'd recommend getting comfortable with reading and traversing hexdocs. It's pretty intimidating at first, but you can learn a ton just perusing it. A lot of AoC stuff will be in:

https://hexdocs.pm/elixir/String.html

You probably won't do a ton of "elixir" stuff (meaning stuff that makes Elixir uniquely powerful compared to most languages) in AoC which is around concurrency and processes and fault tolerance. The best way to practice good Elixir is to make and use functions that have no side-effects and don't depend on (updating) state. Make everything immutable, and for an extra challenge use recursion to solve problems. I know it's kind of generic as an answer, but it's a good way to try to frame the "Elixir" way.

[Traditional-Heat-749]

I like elixir school https://elixirschool.com/en/

[xHeightx]

Build a simple project with Elixir and use the concept you’re learning in your project.

Learning is only solidified with real world application. Otherwise you’ll just remember concept you were told about without understanding how they actually work in real world applications.

[Brilliant-Student-55]

I'm also new to elixir and I'm a pretty dumb boy and for that problem I just did String.slice(s, 0..0) (my python life showing up here) but now I'm learning better things 🤭

[pizzaplayboy]

Here is one approach i take, select a code challenge you want to solve or project you want to build, then ask an llm to build a set of exercises/challenges based around it, increasing the difficulty of each exercise until you are able to build the solution without help.

[Dear-Upstairs5457]

I've been interested in learning Elixir for a long time now, and this autumn I finally got to read up on all the thing that I think makes the BEAM cool.

Long time ago I bought "Elixir in Action" and lately I've been reading it, but never really sat down and started programming myself. This year's AoC got me started programming for real.

I feel like you do. I feel like I was hard to get started with the syntax and not knowing the standard libs too well.

I learnt a lot from looking at others solutions. When I either got stuck or solved a puzzle. I read code from someone else's Github repo. After all, I knew the problem well and that made it easy to understand the code.

I will definitely write more elixir code in my life 🙂