For a while now, I’ve been using make as my task runner for my blog. make run to run locally, make deploy to build and push to GitHub pages.
But… the syntax isn’t great for some things and I’ve been working a lot with Rust. So let’s see what just can do!
While continuing to learn a bit more about macros in Rust (previous post), I really want to move beyond the simple declarative macros and get into something a bit more interesting. Enter procedural macros. In a nutshell, procedural macros in Rust, rather than relying entirely on pattern matching and expansion are fully Rust functions.
They take a specific input (a stream of tokens) and output a specific output (a new stream of tokens), but in between they can do just about anything a full Rust function can do. And what’s better yet… they operate at compile time. And because they operate on tokens (rather than a full AST), you can do things that just aren’t syntactically valid in normal Rust. Things like… variadic functions (a la print! or var!) or even crazier things like embedding Python in Rust for … reasons.
Today specifically, I’ve started working through the prod-macro-workshop repo. It’s a series of five examples macros with test cases and some guidance set up to help you get up to speed. I’m going to be working through the first of these: derive(Builder). Now don’t get me wrong. I really have no idea what I’m doing, so don’t take this as an example of how to write a macro. But perhaps by writing this out, it will help me learn it better… and if you happen to learn something as well, all the better!
Recently I’ve been wanting to learn more about macros in Rust. It was always one of my favorite parts of Racket, so let’s see what we can do.
In order to do that, I’ve been following the excellent MacroKata series. It goes all the way through, starting with the very basics, adding in literals and expressions, handling repetition, nesting, and finally recursion.
What I really want to talk about those is the one that I found most interesting: curry!.
Let a Snafu number be a base 5 number with the curious property that in addition to the digits 0, 1, and 2, it has the numbers
-as-1and=as-2. Sum up a list of Snafu numbers.
Given a map with a series of moving walls (that wrap when the hit the edges of the simulation), calculate the fastest route from the top left to the bottom right.
Implement a cellular automaton with the following rules:
NSWE, SWEN, WENS, ENSW, NSWE, …)Given a map and a series of instructions formatted as distance + turn (
LorR), find the final position. Any time you would walk off the edge of the map, wrap to the opposite edge.
Given a series of equations of either the form
dbpl: 5orcczh: sllz + lgvd, determine what the value of the node labeledrootis.
Given a list of numbers
mixthem by moving each number forward/backward in the list based on it’s value. For example, in4, -2, 5, 6, 7, 8, 9moving the-2will result in4, 5, 6, 7, 8, -2, 9. Each number should be moved exactly once in the original order they appeared in the list.
Given a series of given a series of
blueprints, each of which gives instructions for how to build a singlerobotfrom a collection ofmaterialsthat in turn will produce one of a givenmaterialper turn, determine the best order of builds to maximize yourgeode(the most valuablematerial) production for eachblueprintgiven a time limit of24 minutes.