Makefile

Over the past few weeks, I’ve had the absolute pleasure of learning how Makefiles work. They are gorgeous, beautiful, and you will never need a build script again¹²³.

The Problem

The other day I was trying to get rayon, a library for parallelization using an Iterator-like API, to compile on WebAssembly. In a twist no one ever saw coming, the web isn’t multithreaded⁴⁵. Fortunately, the lads over at rayon thought of this and came up with web workers: a cursed API that kinda allows you to run an asynchronous API on another thread⁶.

Ok, so, I go ahead and build my code with rayon enabled and it generates some weird looking JS file in snippets/wasm-bindgen-rayon-{{hash}}/src but I figure it’s ok. I go to run bun dev aaaand… crash.

Apparently, that weird JS file was referencing another JS file that doesn’t exist. yayy!

What?

Apparently, something like webpack⁷ is supposed to automagically resolve the ../../.. to mean ../../../attendance_crypto.js? This obviously doesn’t make any sense so we have a few options:

1. Fix someone else’s code
2. Hacks

Obviously, option two wins here

Hax?

Ok so game plan: run sed -i magic_regex_to_fix_all_problems snippets/**/*.js But how do I game plan? I need this to happen:

• Every time I build the src-wasm project
• I also want to automatically copy the files in dist/ to the frontend, because I’m tired of it

Your clever mind immediately jumps to a build script. Great! Now we have a 1000-line build.rs file that takes a year and a half to build⁸ and copies a few files around and maybe runs that regex if you’re lucky. Bravo, drinks all around⁹.

Introducing: The Makefile

Want to copy a file?

wasm:
  cp -r src-wasm/pkg app/wasm

Two lines of code. run make wasm to copy. That fucking easy. The C developers were right. This is genius.

Want to do a bit more?

wasm:
	@echo "=== Building WASM package"
	cd src-crypto && rm -rf pkg && wasm-pack build --target web --release
	@echo "=== Copying package files"
	rm -rf app/wasm
	cp -r src-crypto/pkg app/wasm
	@echo "=== Patching workerHelpers.js files"
	sed -i 's|\.\./\.\./\.\.|../../../attendance_crypto.js|g' app/wasm/snippets/*/src/workerHelpers.js

This now builds the project, copies the files, patches the broken parts, and cleans up after itself, all faster than that build.rs it took you a decade to write.

And it’s not that build.rs is a bad thing necessarily, I mean, it has it’s uses¹⁰, but no one really needs that complexity.¹¹

Makefiles are the perfect, all-in-one solution for monorepos in need of a way to move compiled files around, all without the overhead of a programming language¹², compile times¹³, or whatever the hell this is. As an added bonus, basically every C developer will be on your side¹⁴.

Footnotes

1. exception: programmatic stuff that you need a full programming language for (e.g. schema generation) ↩

2. exception: when a library you’re using requires a build.rs (cough prost cough) ↩

3. ok there are a lot more exceptions but goddamnit if Makefiles aren’t great ↩

4. exception: web workers and service workers ↩

5. exception: webcrypto probably? depends on the implementation I’d say. also probably webgl/webgpu, canvases, ffmpeg, networking and I/O, and various other things. the point is that there are limited options for runnning arbitrary code on multiple threads, which is what counts. ↩

6. not really, it’s IPC all the way down. the best you can do with this is define a typescript namespace and type your worker to hell and hope it doesn’t explode? ↩

7. i remember webpack a little bit from my react days oh so long ago ↩

8. Someone at Rust HQ should really consider fixing it’s build times (cough dynamic libraries cough) ↩

9. non-alcoholic of course ↩

10. * prost intensifies * ↩

11. pro tip: if you ever find yourself needing a build.rs file, you’re probably doing some kind of code generation; and by then you should probably be using a proc-macro. Just saying. ↩

12. in my defense, bash barely counts as a programming language ↩

13. python: … ↩

14. do they use cmake now? I’m not sure… ↩