READ & REASON
Your field notes saved on this device
Saved in this browser only.YOUR LOCAL CODE
No exercise evidence loaded.
Visual practice and local code checks are separate. A passing check does not assess your explanation.SYSTEMS, MADE VISIBLE
The machinery beneath
your program.
The same objects. The same answer.
Why can one traversal do more memory work?
Build a small allocator, follow pointers through a cache, and write two ways to collect a heap. Then test what your explanation can—and cannot—say about a real collector.
Begin with objects ↗A SMALL PUZZLE TO STARTFive slots free.
Five slots free.
Room for three?
AA—B—CC—DD——
An object needs one contiguous interval. Can this request fit without moving anything?
Read and predict here. Download the Go project for coding with Node.js 22+ and Go 1.22+. Extract it, run node start.mjs and follow the README. Keep your work/ folder when updating.
Notes and predictions stay in this browser. Imported traces and benchmark files are read on this device and are never uploaded.
OBSERVE A SMALL MODEL
JSON from your local Go run · stays in this browser
Per lesson: up to 200 saved predictions and 1000 explanations. At the limit, export your work before starting a new journal. Existing records are never removed automatically.