Unsafe Rust code inherits a contract that safe code does not: it must maintain memory safety even when a panic unwinds through it. This is called minimal exception safety, and violating it produces undefined behavior. The second half of the problem is strategic: sometimes the right response to a potential panic is not to unwind…
When a Rust value moves out of its original location, the compiler cannot know at compile time whether the original location still needs to be cleaned up. The solution is drop flags—hidden boolean variables that track initialization state at runtime. This machinery is mostly invisible, but understanding it is essential for reasoning about panic safety,…
Package management is the daily rhythm of working with Yarn. You add a library to solve a problem, upgrade it when a bug is fixed or a feature lands, and remove it when the dependency is no longer needed. Each of these operations modifies two files—package.json and yarn.lock—and the commands that perform them differ significantly…
Every dependency you add, upgrade, or remove triggers a two-file update: package.json records the intent (a version range like ^4.18.0), and yarn.lock records the reality (the exact version and integrity hash that was resolved). The manifest is what you write; the lockfile is what Yarn writes. Understanding this division is the difference between a project…
Every Yarn project begins with a single file. Before dependencies are installed, before scripts are run, and before lockfiles are generated, there is package.json. This file is the manifest—the contract between your project, the package manager, and anyone who clones the repository. Running yarn init is the first command in any new project, and understanding…
Installing Yarn used to mean a single global command. That era is over. Modern Yarn—versions 2, 3, and 4, collectively called “Berry”—is designed to be installed per-project, not globally. The tool that makes this possible is Corepack, a Node.js utility that intercepts yarn commands and routes them to the exact version declared in your project’s…
The JavaScript ecosystem has never had a single package manager. For years, npm was the default—it shipped with Node.js, and it worked. But in 2016, Yarn arrived with a promise of speed, determinism, and better dependency management. Nearly a decade later, the landscape is more complicated: Yarn has evolved through multiple major versions, npm has…
A repository without a README is a closed door. Visitors arrive, see a list of files with cryptic names, and leave. The README is the first thing GitHub renders on the repository home page, and it is the single artifact that determines whether a stranger becomes a user, a contributor, or a bounce. This chapter…
A repository is the container that holds a project’s files and their complete revision history. Creating one on GitHub is a four-step form: name it, choose who can see it, optionally seed it with starter files, and click create. The visibility choice—public or private—is the only decision that cannot be changed without consequences, and the…
GitHub disabled password authentication for Git operations over HTTPS in August 2021. Passwords are reused, phished, and leaked in bulk; the replacements—SSH keys and personal access tokens—are revocable, scoped, and often time-limited . The choice between them is not about which is “better.” It is about which one matches the workflow: SSH keys for your…