Cheng Lou open-sources Handwired: hand-written weights turn code into training-free neural nets
dotey · x · 2026-10-16
dotey shares a tutorial video on Handwired, an open-source "toy project" by Midjourney engineer and former React core team member Cheng Lou that rewrites if-else logic and loops into hand-written neural network weights — no training required, with outputs exactly matching the original JavaScript.
- How it works: e.g. result = a > 4 ? 10 : 12 becomes relu(a - 4) - relu(a - 5) as a 0/1 switch combining both branches; all branching folds into matrix multiplications plus ReLU.
- Precision: only trained nets are probabilistic; hand-written weights are fully deterministic.
- Demos: a Mini OS desktop (drag, resize, scroll, text input, animations) driven by a 130-layer, 9,909-weight "network" running in-browser on CPU with zero training, plus real-time search over 100k items.
- The video covers leap years, FizzBuzz, tiered pricing, Game of Life and Snake, and compares this to Transformers, browser training, debugging, and CPU vs GPU performance.
- Video produced with Claude Opus 5.5 + a Skill, narration via Gemini 3.8 TTS.
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