programming

Lets say you want to store two different types of objects in 1 container. Simple right? Just slap those puppies in a tuple and you're good to go:

let list: Vec<(u8, f32)> = vec![(255, 20.0), (10, 37.0)];

But what if you wanted to include elements of two different types in arbitrary orders? Thankfully, there's sum types for that:

pub enum Val {
    A(u8),
    B(f32),
}

... {
    let list = vec![Val::A(255), Val::B(20.0), Val::B(37.0), Val::A(10)];
}

One small problem. That's wasteful.

Seriously, is there a good reason for this? I feel like I'm going crazy because almost every language doc I've looked at is legitimately awful in a bunch of obvious ways. It's not uncommon to see third party libraries updated by a single person that are better structured, more thorough, with better layouts than the official documentation upheld by the language team itself.

Partial borrows across function boundaries don't really work in Rust. Unfortunately, that's kind of a major issue. There are workarounds, some are outlined here, but all of them come with pretty major drawbacks.

Oh how naive I was when I thought I'd be moving on to pathfinding and abilities. I had hoped some of the game's mechanics would function better in isolation, so I could gradually add complexity on top of the tracer bullet in a modular way. Unfortunately, that doesn't seem possible without a huge refactoring burden every time I add the next layer. It'll be more worth my time to properly architect it right now, and build it from the ground up with all of the systems it'll need.

A while back, I made a small application meant to demonstrate some important principles about RTS design, namely that unit stats in a vacuum can be very misleading. As a quick example, stalkers have ~9.7 dps on paper. When fighting marines though, their effective DPS drops to ~8.4 (8.2 with combat shields) due to overkill. That's about the same DPS as a sentry. Unfortunately, there's only so much info that can be extracted from a Time To Kill calculation between two units.

I encountered a neat example recently while solving Advent of Code 2015, day 6. The problem can be boiled down to "There is a 2D array of values. Given a range and instruction, apply the instruction to all values in that range. How many values are 'on' at the end?". There are only 2 possible states for each value: on and off, and only 3 possible instructions: on, off, and toggle. I won't focus too much on parsing the input or the structure of the algorithm here, I just want to investigate the hot loop which applies the instruction to each value.

I've seen this question come up a few times on r/ssbm and while I've given hand-wavey answers before, I find myself in a good place to answer more rigorously now. We can break this question down to more basic ones: "how many bytes of replay data correspond to a single frame of gameplay?" and "how many bytes in the replay are unrelated to frames?". From there, we can estimate a duration by simply translating the 16.667ms per frame to minutes and seconds.

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