Scripts

A single .rs file can carry its own dependencies:

#!/usr/bin/env -S rune script
---cargo
[dependencies]
serde_json = "1"
---
fn main() { println!("{}", serde_json::json!({ "hello": "world" })); }

rune script hello.rs [args] (or ./hello.rs with the shebang) builds it as a throwaway package under $RUNE_HOME/scripts/ and runs it; stdout is the script's output and nothing else, and its exit code is Rune's. Because dependencies come from the store, a script whose dependencies any project has built before starts in about 0.15 s. Line numbers in errors match the file.