In this post, we will walk through Tim Visee’s solution to the day 5 Advent of Code Rust problem. The aim of this blog post is to not explain the solution to this problem, which is already explained in other blogs very well. Instead, I aim to explain the several idiomatic expressions in Tim’s terse Rust code for folks new to Rust.

Part One

Tim’s Code

include_str! and include_bytes!

These macros load the contents of a file into the codei, but at compile time itself! The variable will have a type &'static str! (see docs) ADD NOTE ON SPACE REQUIREMENTS? Is it better to iterate line by line at runtime?


nom is a Rust crate for fast parsing of byte data. As we can see in this commit, using nom significantly sped up the code. How does it make this difference?

The original code had three split_once calls and several unwrap and parse calls. Even in --release mode, the compiler cannot optimize away the safety checks and the bounds checks in these calls (see godbolt sample here).


So this is that blog I never ended up finishing.