SystemsGuide
Unsafe Rust Explained and What the Keyword Really Promises
A guide to unsafe Rust: what the keyword allows, the contract it creates, how to wrap it in a safe API, how to check it with Miri and where it is actually needed.
15 min read
Topic
Rust
The language itself: ownership, lifetimes, error handling, Serde and the idioms that make the borrow checker feel like help.
Rust
Rust Error E0502 Cannot Borrow as Mutable and Immutable
E0502 appears when you hold a reference into a value and then change that value. See the typical Vec case, why push is the danger, and four ways to resolve it.
7 min read
Systems
Rust Panics Without Std and Choosing a Panic Handler
In no_std a panic handler is mandatory. Compare panic-halt, panic-abort, panic-probe and a custom handler, and how panic = abort and the core panic machinery fit together.
3 min read
Tooling
Reading Rust Backtraces and Setting the Right Variables
A panic prints a message and one line of context. Set RUST_BACKTRACE to see the stack, find your frames in the noise and know what debug symbols change.
3 min read
Web
JSON Requests and Responses in Axum With Serde Step by Step
Accept and return JSON in Axum with the Json extractor and Serde: validate input, set status codes, handle bad bodies and avoid common content type mistakes.
7 min read
CLIGuide
Build a Todo CLI in Rust With Serde and a JSON File
Build a todo list CLI in Rust with clap subcommands, serde JSON storage, stable ids, atomic and durable saves, and a file lock that stops concurrent runs from losing items. Every claim measured.
17 min read
Rust
Rust Error E0499 Cannot Borrow as Mutable More Than Once
E0499 means two mutable references to the same value were alive at once. Learn to spot which two, and fix it with scope, splitting or an index.
6 min read
Web
Axum Error Handling With IntoResponse and Custom Errors
Make every Axum handler return Result with one AppError enum that implements IntoResponse, so the question mark works and clients get consistent JSON errors.
7 min read
Rust
Rust Error E0382 Borrow of Moved Value and Three Fixes
Rust error E0382 means a value was moved and then used again. Here are the five fixes in the order to try them, with the code for each.
7 min read
Architecture
Error Boundaries Between Layers in a Rust Application
Each layer of an application should speak its own error type. Convert at the boundary with From, keep causes for logs and map to HTTP codes only at the edge.
2 min read
Rust
Copy Versus Clone in Rust and Which Types Are Copy
Copy is an implicit bitwise duplicate and Clone is an explicit call that can do real work. Know which of your types should have which, and what each costs.
7 min read
Rust
Ownership in Rust Explained With a Mental Model That Holds
Ownership is three rules the compiler checks for every value. This post builds a mental model from them and uses it to predict what compiles before you run the compiler.
8 min read
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