babygo

When I learned Rust I loved rustlings: it hands you broken code and a compiler, and you are not done until the check passes. When I got to Go, the closest equivalent I found was golings — and honestly, it wasn’t very good. Meanwhile Go by Example is 85 complete, beautifully annotated programs that are excellent to read — but nothing is ever asked of you.

So I combined them. babygo is Go by Example with the load-bearing lines cut out. You put them back. The runner is a small Go CLI called gorun:

1git clone https://github.com/krushiraj/babygo && cd babygo
2make watch

make watch drops you into the first unsolved exercise and re-runs it every time you save — with a diff of expected vs. actual output, the exact differing characters highlighted, hints on demand, and single-key controls to re-run, reset, or move on. It needs Go 1.26+ and nothing else: no dependencies, no network after the clone.

All 85 are machine-checked

Exercises are checked by running them and diffing stdout — in Go by Example, the output is the lesson. Where exact diffing can’t work, each exercise declares a mode: regex for lines with timestamps or random values, test for go test-driven exercises, unordered where Go’s map ordering shuffles lines. The modes weren’t guessed — a capture command runs every solution ten times and observes what actually varies.

I was stubborn about one thing: no “tick the box to say you did it” mode. The design allowed for one, assuming exercises like http-server, tcp-server and signals couldn’t be harness-driven — they block forever or want a second terminal. Turns out they all can: httptest covers HTTP, a port-0 listener with deadlines covers TCP, and signals sends itself the interrupt. An “I promise I solved it” checkbox is exactly what a learner reaches for on the exercises that would have taught them the most.

There’s also a make verify honesty check asserting the two things that matter for all 85: every solution passes its own checker (the exercise is solvable), and every shipped exercise fails it (there’s something to solve).

Not a fork

Go by Example isn’t forked — it’s cloned read-only, and the exercises are a derived artifact recording the upstream hash they were cut from. A fork would make every upstream merge conflict precisely where the lines were cut; instead make sync just reports what moved upstream so exercises can be re-cut. All 85 programs and all of the teaching are Mark McGranaghan and Eli Bendersky’s Go by Example (CC BY 3.0) — this project only removes lines and adds a checker.