Foundry

A learning repo for Go, TypeScript, Python and Scala 3, run from day one, built around retyping code from memory rather than reading about it.

Why it works this way

Reading a lesson feels like learning and mostly is not. The retention here comes from one mechanic: you type the canonical example, then a session or two later you type it again with the reference hidden, and a diff tells you exactly what you lost.

Everything else — the lessons, the mechanism deep-dives, the notes — exists to make that example worth having in muscle memory.

The loop

Stage	You	Checked by
Read	one screenful on what it is and why	—
Mechanism	what actually happens underneath	—
Type along	retype example.go with it visible	foundry check
Recall	retype it later, from memory	foundry check
Apply	build something small with it	tests

Starting a track

foundry focus go     # or ts, py, sc

Then open the repo in Claude Code and say go. That is the entire setup — there is no per-module scaffolding step, and nothing to create by hand. The lesson, the example, the drill schedule and the notes are all written during the session.

foundry guide prints the full manual, and it is offered automatically on a fresh track.

Using it

Open the repo in Claude Code. A hook prints where you are:

foundry — go · tier 0 syntax
  now   00-values-and-types           read → mechanism → type-along
  due   2 recall drills               01-operators, 02-control-flow
  lc    two-pointers · 3 unpulled

Say go. That is the whole interface. Progress, drills, and notes are written for you at the end of a session — there are no bookkeeping commands to remember.

CLI

foundry guide               the full manual
foundry status              where you are, what is due
foundry focus <lang>        pick the active track (go, ts, py)
foundry drill <lang> <mod>  set up an attempt (add --blind to hide the reference)
foundry check <lang> <mod>  diff your attempt against the reference
foundry lc                  dispense a leetcode problem
foundry iv                  dispense an interview question
foundry lc reset            wipe leetcode progress only
foundry iv reset            wipe interview progress only

<lang> is go, ts, py or sc. <mod> accepts a prefix, so 00 resolves to 00-values-and-types.

Build it once: go build -o foundry ./cmd/foundry

Interview questions

foundry iv works the same way the drills do: it hands you a question and a blank file, you write the answer out in full, and only then does foundry iv ref reveal the model answer. It refuses to reveal if you have not written anything.

This is deliberate. Answering in your head feels like knowing; composing three paragraphs under a question you have not seen is what an interview actually asks for, and the gap between the two is the whole point.

Toolchain

Pinned via .nvmrc (Node 24), .python-version (Python 3.14.7) and .sdkmanrc (Scala 3.6.4, JDK 17). Go is 1.27. TypeScript runs under bun and Scala under scala-cli, so neither needs a build step.

Layout

foundry.json    curriculum spine, 25 modules per language across 6 tiers
tracks/         go/, typescript/, python/, scala/ — created as you reach them
leetcode/       97 problems, 15 patterns, standalone and resettable
interview/      31 questions, written answers, standalone and resettable
vault/          Obsidian notes, written as a side effect
state/          progress, drill schedule, session logs

History

v1 of this repo generated 858 files across seven languages and recorded zero attempted exercises. It is preserved at the foundry-v1 tag. The lesson taken from it: content is cheap to generate and expensive to consume, so nothing here is generated before you reach it.