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playground-workflow

Playground workflow

Last reviewed May 28, 2026 Content v20260528
Track mode
server_compiled
Means
Compiled runner
Reading
~1 min
Level
beginner

This lesson

This lesson teaches Playground workflow: the syntax, APIs, and habits you need before advancing in Rust.

Teams ship Playground workflow on every Rust codebase—skipping it leaves gaps in debugging and code reviews.

You will apply Playground workflow in contexts like: Infrastructure CLIs, proxies, game engines, blockchain nodes, and latency-sensitive backends.

Write Rust with fn main(), click Run on server—the dev runner compiles main.rs with rustc and runs the binary; fix borrow errors from stderr (requires Rust toolchain; LEARNING_RUNNER_ENABLED=true). Also read rustc errors literally—they point at the exact borrow or move violation.

At the start of the track—complete before lessons that assume you understand the server playground.

Get the most from each lesson's compiled editor—the same habits that transfer to VS Code, rust-analyzer, and CI running cargo test.

Recommended workflow

  1. Read the concept section before editing code.
  2. Click Run to compile with rustc and execute.
  3. Use println! and {:?} for debug output.
  4. Change one idea at a time; read borrow checker messages carefully.

What the runner can and cannot do

  • Can — single-file fn main with the standard library
  • Needs local setup — Cargo workspaces, async runtimes, WASM builds

Review JavaScript, Java, and C++ for comparison context.

Self-check

  1. What macro prints to stdout in Rust lessons?
  2. What is the first step when the borrow checker rejects your code?

Challenge

First compile and run

  1. Click Run with the default code.
  2. Confirm output appears in the terminal.
  3. Add a second println! with your name.

Done when: the terminal shows the default message and your custom line.

Challenge

Verify compile output

  1. Run the default program.
  2. Confirm output in the terminal.
  3. Introduce a move error (use a String after move) and read the message.
  4. Fix and run again.

Done when: you see a clear compile error when broken and successful output after fixing.

Interview tip Lesson completion confidence

Can you explain this lesson in 30 seconds without reading notes?

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Playground

Runs on the configured server runner (dev: npm run runner with LEARNING_RUNNER_ENABLED=true). Output appears below the editor.

Check yourself

Multiple choice — immediate feedback.

Discussion

Past discussion is visible to everyone. Only logged-in users can post comments and replies.

Starter discussion topics

  • rustc error read how?
  • fn main required?

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