# micro-gopt

A go hand-reimplementation of <https://karpathy.github.io/2026/02/12/microgpt/>.

Original python is included in the repo for reference against bitrot.

To use: `go run cmd/main.go input.txt`

Differences between the Go and the Python, as well as notes more generally:

* The GPT is implemented as a package and, separately, as a command-line wrapper that calls it, just to keep the algorithm separate from the invocation details.
* The Value class is more type-safe in go, using values everywhere as opposed to mingling floats and values in the localgrad tuple.
* The Value struct has actual tests confirming the backward propagation logic.
* When writing the Value struct and its methods, I accidentally swapped the order of the values in the `localGrads` slice in `Mul` and tore my hair out trying to figure out where the bug was. When I broke down and asked copilot to "compare these two implementations and tell me how they differ," it managed to find the error -- but also reported three non-existent differences and told me that `slices.Backward()` doesn't exist.
* Initial pass translating the linear algebra functions has me worried that all those value structs aren't going to be very fast...
* Had to implement weighted random choice. <https://cybernetist.com/2019/01/24/random-weighted-draws-in-go/> made that relatively straightforward; it's a neat algorithm.

First proper run:

![well, um...](./doc/first_time.png)

Something's not right here, unless the hit new baby name is `kaaaaasehaaeaaal`.