# Command-line interface Building or installing Nybl 0.4 requires Rust 1.88 or newer. Install the current Nybl command-line tool from crates.io: ```sh cargo install nybl-cli ``` ## Run a script ```sh nybl run app.nybl ``` `nybl run` uses the bytecode VM by default. It runs the warning pass before execution, resolves `std.*` from the bundled standard library, and resolves other module paths relative to the script. Use the tree-walker when debugging engine behavior or minimizing the active runtime: ```sh nybl run --novm app.nybl ``` Both paths render the same source snippets, carets, hints, module context, and warnings. ## Compile a native executable ```sh nybl compile app.nybl nybl compile app.nybl -o my-app ``` The command transpiles Nybl to Rust, creates a temporary Cargo project, builds a release binary, and copies it to the requested output path. `cargo` and a Rust toolchain must be available for this step. By default, `app.nybl` builds `./app`; an extensionless source such as `app` builds `./app-bin` so the source can never be mistaken for its output. On Windows, native outputs also receive the `.exe` suffix. An explicit output path that resolves to the source itself is rejected before the build starts. Use `-o` with a distinct path instead. Use `--emit-rs` to stop after transpilation: ```sh nybl compile --emit-rs app.nybl -o app.rs ``` Use `--keep` when building a binary to retain the scratch Cargo project for inspection after the command finishes. ## Open the REPL Either spelling starts the persistent interactive session: ```sh nybl nybl repl ``` See [REPL](https://nybl-lang.com/docs/repl/index.html.md) for multiline input, live bindings, history, completion, meta-commands, and piped transcripts. ## Help and version ```sh nybl --help nybl --version ``` Argument and usage errors exit with status 2. Parse, runtime, module, and build failures exit non-zero after rendering their diagnostic.