Over 4 years ago, I proposed the idea of native Cargo Script support in a blog post. Today, I posted the stabilization PR against Cargo: https://github.com/rust-lang/cargo/pull/16569
This allows Cargo to be a shebang "interpreter", reading manifest content from a new syntax in Rust code called a "frontmatter". This is helpful for
- Better, self-contained reproduction cases for bug reports
- More easily communicate using code snippets that use dependencies in blog posts, chat, books, etc
- Lower barrier for experimenting with an idea. While it isn't a REPL, it can cover a lot of the gap of not having one.