- Python – Tuples
Tuples and why an immutable sequence earns its place next to the list. Unpacking, returning more than one value, the starred target, named tuples, and the one-element tuple that catches everybody.
- CompletableFuture
CompletableFuture runs work on another thread and lets you describe what should happen when it finishes — without blocking to wait for it. It is how you stop making a caller wait for three slow things in sequence when they could happen at once. Starting work supplyAsync when you want a value back,…
- Terraform – HCL Syntax You Will Actually Use
HCL is small, and this is the part of it you need. Blocks and arguments, the type system, string interpolation and heredocs, the functions worth memorising, `terraform console` for trying an expression without an apply, and `terraform fmt` so nobody reviews your indentation.
- React Native – Structuring a Real App
The folder layout that survives a second developer. Feature-first rather than type-first, why route files should name a screen and never implement one, path aliases so nothing imports `../../../`, a single shared type contract with the backend, and the rule that keeps it honest: anything two features need moves down, never sideways.
- TypeScript – any, unknown, never and void
The four types that are not values. any switches the checker off and spreads; unknown is the safe version and forces you to prove what you have; never is what a function that does not return has, and the trick behind exhaustive switches; void is not undefined. With the catch (err: unknown) block that made the case.