writeup in readme

README.md

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 # adventofcode2024
 
-Advent of Code 2024
+This repo contains [typescript][tc] solutions for the
+[Advent of Code 2024][aoc2024] puzzles. The scripts are written to executed in
+the [Deno][deno] runtime.
+
+## Context
+
+I have been using Deno for a while for personal scripting needs. Also, I always
+wanted to finish the Advent of Code puzzles. So, I decided to give a shot at
+solving this year's AoC using typescript. This way I can improve my typescript
+as well as solve the puzzles.
+
+## Thoughts
+
+### Typescript
+
+So far, my experience with typescript has been subpar at solving AoC puzzles.
+Deno is a great runtime, but the typescript has been a bit of a pain to write
+data structures and algorithms. Coming from the Rust ecosystem, I missed some
+features very much.
+
+- Data is passed using references implicitly. If I change some value in a
+  function, it changes the value in the caller function. Rust uses immutable
+  borrow for this.
+- No hash function for objects. The `Map` and `Set` data structures uses object
+  pointers for keys. So I can have `new Set([[1, 2], [1, 2]])` with size 2
+  because the two arrays are different objects, even though they have the same
+  values. I had to use string keys for objects when using them as keys in a map
+  or set.
+- No standard data structure libraries. I had to maintain my own set, maps and
+  other data structures.
+  - Must say that `jsr:@std/data-structures` helped me with `BinaryHeap`.
+- Not strong typing and type inference. I had to write concrete types at some
+  places.
+- Not strong pattern matching. I missed Rust's pattern matching very much.
+- No pairs, tuples or constant size arrays.
+- Footguns like `==` and `===` or `const elem of array` and
+  `const elem in array`.
+
+### Deno
+
+Deno has been great. I would have stopped using typescript if it weren't for
+Deno. The runtime is great, and the `jsr:@std` library is very useful. None of
+my solution uses any external dependencies except `jsr:@std`. Deno's test and
+assert libraries allowed me to test my solutions. I can use a single binary for
+everything. The `lint` and `fmt` commands kept my code clean.
+
+[aoc2024]: https://adventofcode.com/2024
+[tc]: https://www.typescriptlang.org
+[deno]: https://deno.com