Solving Advent of Code at compile time with Rust macros | Hacker News Reader

Solving Advent of Code at compile time with Rust macros

doublefree.bearblog.dev

24 pointstodsacerdoti9 comments

> Not only is the python solution barely legible

The article then proceeds to produce barely legible code, but it's in Rust instead! I would leave out own-goals like this, it detracts from the content.

It's full of stupid comments. E.g. the python implementation has this attached.

```py """Warning: This code completes in a shocking O(n log n) time complexity and allocates memory with reckless abandon""" ```

How shocking that sorting is an O(n log n) algorithm.

Edit: he then goes on to use bubble sort.

I think there might be a large amount of tounge in cheek with this blog post, but it doesn't really land.

Technically, because the bubble sort is implemented at compile time the program is infinitely faster.

The answer is produced as a compiler error and so there is zero runtime at all.

I thought it all completely landed, that it was very obvious what you were doing, and that it was very funny as well as being real neato. Frankly I would probably put negative stock in the opinion of anyone who sees you accusing that python code of being hard to read and thinks you're remotely serious.

Hey! I wrote this. The python being barely legible is my own fault, as the one who wrote it.

The whole post is written to be a little ridiculous, but I must not have gotten that across =(

I agree with you. In real life, python is absolutely a better choice than trying to write a Rust macro to produce the result as a compiler error.

I added a footnote to the end of the referenced paragraph to say that python is great.

Is this really what Rust macros look like?

This is one kind of macro in Rust: declarative macros [1]. The other kind of macros in Rust are procedural macros [2]. Both are widely used in idiomatic Rust. And even within the procedural type of macros, there are different categories of macros (i.e., function-, or attribute-like macros).

[1] https://doc.rust-lang.org/book/ch19-06-macros.html

[2] https://doc.rust-lang.org/book/ch19-06-macros.html#procedura...

Yes, and I've seen them in production. Once you learn the rules, you can parse them reasonably well in your head but it is still really confusing at a glance.

It is! Although they are being used in a really weird and not normal way here.

I found "The Little Book of Rust Macros"[1] to be a really good resource for getting started with Rust's declarative macros.

[1]: https://veykril.github.io/tlborm/

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