Master any language,
one gotcha at a time.
Every track runs foundations → intermediate → advanced → expert. No toy snippets — ownership traps, type coercion surprises, off-by-ones, and the production bugs that actually bite.
4
tracks
51
topics
1020
questions
Foundations
syntax, types, control flow
Intermediate
collections, functions, errors
Advanced
concurrency, generics, memory
Expert
unsafe, macros, perf tuning
## tracks
Pick a language
4 tracks · sorted by topic count
js
A complete quiz-based curriculum covering JavaScript from first principles to expert-level, production-grade knowledge. Every quiz is self-contained — read the explanations, not just the answers, to build a full mental model of the language.
rust
A complete quiz-based curriculum covering Rust from first principles to expert-level, production-grade knowledge. Ownership and the borrow checker are the spine of the language — the curriculum is sequenced so every later quiz assumes you can reason about them.
python
A complete quiz-based curriculum covering Python from first principles to expert-level, production-grade knowledge. Python's simplicity hides a lot of nuance — this track is built around the surprises that trip up even experienced developers.
lua
A complete quiz-based curriculum covering Lua from first principles to expert-level, production-grade knowledge. Lua's minimalism is deceptive — nearly everything (objects, modules, namespaces) is built from one primitive, the table, and this track is sequenced around the handful of mechanisms (metatables, closures, coroutines) that make that possible.
## why quiz://
Built for gotchas, not trivia
Production-grade scenarios
Every question is drawn from real bugs, not toy snippets — the kind that survive code review and bite in prod.
Progressive difficulty
Basic recall → edge cases → best-practice judgment calls, ordered so every quiz builds on the last.
Explanations that teach
Collapsed answers explain the mechanism — evaluation order, coercion rules, borrow rules — not just the label.