- Terraform – What It Is and Why It Exists
Start here. What infrastructure as code actually buys you over clicking around a console, where Terraform sits next to CloudFormation, CDK, Pulumi and Ansible, the 2023 licence change and what OpenTofu is, the exact versions this track is written against, the application the AWS lessons deploy, and the full lesson index in reading order.
- React Native – Navigation
Navigation is not a router over URLs — it is a stack of native screens. Expo Router makes the folder structure the navigation graph: `(tabs)` groups without adding a URL segment, `[orderId]` declares a dynamic route, `+not-found` catches the rest. Stacks versus tabs, passing and reading params, `push` versus `replace`, and why route files should be one line long.
- Collectors class
A stream pipeline has to end somewhere. collect is the general-purpose ending, and the Collectors class supplies the recipes — turn this stream into a list, a map, a grouped report, or one joined string. There are dozens of them and you do not need dozens. Six do almost all the work in practice,…
- Omega, Theta and the Rest of the Notation
Big O is an upper bound, Omega is a lower bound and Theta is both at once. What each one actually claims, why saying an algorithm is O(n^2) does not mean it is slow, and the difference between a bound and a case that people conflate constantly.
- React – Forms and Controlled Inputs
A controlled input is one whose value comes from state, which is what makes validation, formatting and disabled submit buttons possible at all. value plus onChange, one handler for many fields, checkboxes and selects and radios, submitting without reloading the page, and useId for labels that actually work.