aoc language post

src/content/posts/2024-12-02-aoc-language.md

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+---
+title: The advent of code language
+date: 2024-12-02T11:08:41.157Z
+tags: [pl, advent-of-code]
+---
+
+It's December, which means ~~grad school apps are due soon~~ [Advent of Code (AOC)][aoc] has started.
+AOC is an [advent calendar] with increasingly difficult coding challenges from December 1 up until Christmas.
+
+[aoc]: https://adventofcode.com/
+[advent calendar]: https://en.wikipedia.org/wiki/Advent_calendar
+
+Usually, people use this as an excuse to learn a new language.
+I did this a couple years back with [aoc2022].
+
+[aoc2022]: https://git.mzhang.io/michael/aoc2022
+
+Since I have started to play around with programming language design and theory a bit, I decided to take a stab at writing a new language and using it to crack advent of code challenges.
+So far, I have an interpreter that runs very minimal JS-looking language which is capable of solving the first day.
+For example, here is the code for the second part of day 1, in my language:
+
+```
+input data = "1.txt";
+
+let lines = data.splitlines();
+let pairs = lines.map((s) => {
+  map(s.splitwhitespace(), (n) => { parseint(n) })
+});
+
+let lists = pairs.transpose();
+let left = lists[0];
+let right = lists[1];
+
+let counts = left.map((n) => {
+    let one_count = right.map((m) => { if m == n then 1 else 0 });
+    let s = one_count.sum();
+    n * s
+});
+
+print(counts.sum());
+```
+
+The source code is [here][code].
+
+Few things to note:
+
+- I've been enamored by the idea of [UFCS] for a while, and my interpreter implements a rather naive version of it.
+  However, I'm curious about how this scales and how it will interact with polymorphic functions or variable namespaces.
+- The parser is still currently very broken. This is why the `pairs` definition couldn't just read
+  ```
+  let pairs = lines.map((s) => s.splitwhitespace().map((n) => parseint(n)));
+  ```
+- Functions like `splitlines`, `parseint`, `map`, and `transpose` are still implemented using intrinsics.
+  They will be moved to a "standard" library once modules have been figured out.
+
+In a few weeks, I will try to flesh this language out into a playground for some programming language ideas I've been meaning to try to implement, such as algebraic effects.
+Stay tuned for further updates!
+
+[code]: https://git.mzhang.io/michael/aoclang2024
+[ufcs]: https://en.wikipedia.org/wiki/Uniform_Function_Call_Syntax