01_python_model

Module 01 — Python Language Model & Algorithmic Foundations

Status: light infra (by design — least role-relevant; see docs/scope-cap.md), but now carries the concept ramp from the interview-prep package: a clean climb from never-programmed to the two interview-relevant ceilings (problem decomposition and the Python data model). The runnable infra stays minimal on purpose; the explanatory depth is docs-first, exactly as the scope cap prescribes.

The ladder (barebones beginner → ceiling)

This module is two tracks standing on one shared foundation. Read top to bottom:

• Rung 0 — Foundations · notes/python-foundations.md — for someone who has never programmed: variables, lists, dicts, loops, functions, self.
• Rung 1a — Python data-manipulation patterns · notes/array-string-patterns.md — for someone who can read the code and now learns why the patterns work (hash map, sliding window, two pointers, sort+dedup).
• Rung 1b — Data-model track · exercises.py + tests — the same foundation in the OOP direction: mutability, the dunder protocol, the sequence interface.

Tracks 1a and 1b are parallel, not sequential: 1a builds problem-decomposition instinct (Python data manipulation), 1b builds Python-data-model fluency (the language-model strand). Both are reachable directly from rung 0. The notes cross-link to the code (python-foundations §3/§9/§10 point at exercises.py's hashability, mutability, and class/self), so the concept doc and the runnable proof stay one click apart with no repeated prose.

What's in this folder

• notes/python-foundations.md — the never-programmed on-ramp (concepts only).
• notes/array-string-patterns.md — array/string algorithmic patterns + trade-offs.
• exercises.py — MutableDemo, Vector2, MiniSequence (the data-model ceiling).
• tests/test_python_model.py — prove-it tests.

Infrastructure

Local Python only (no Docker services).

Run

uv run pytest modules/01_python_model/tests

Native Windows: .\tasks.ps1 test (or run pytest from the project .venv directly).

Prove-it exercises

1. Mutability drill — list/dict mutation vs frozen Vector2 (the runnable form of python-foundations.md §9, in-place .sort()).
2. Dunder methods — __repr__, __eq__, __hash__ on Vector2 (the runnable form of why a value can be a dict key — python-foundations.md §3).
3. Data model API — MiniSequence supports len, indexing, iteration (the protocol behind python-foundations.md §2/§5).

The data-manipulation patterns note (notes/array-string-patterns.md) is explanation-only by design: the scope cap keeps Module 01 light, and the drill for these patterns asks you to reason about an invariant and a trade-off, not to ship a graded LeetCode harness. Each pattern in the note carries its own invariant and the bug it prevents — that is the two-question bar for this track.

Further reading

• docs/curriculum.md — Repo module 01 (Python language model) — the curriculum module the data-manipulation patterns in notes/array-string-patterns.md serve