cargo-script-mvs VS xshell

The eRFC was intentionally light on details so the Pre-RFC / IRLO thread and the demo best reflect what we hope to accomplish which are pretty detailed as-is.

> A) is easy to write one off scripts that do a job fast, with minimal thinking and effort. I am thinking of Python and Ruby. For me I can write code with high velocity in these languages.

Once I wrap up some other projects, I plan to explore this space a little bit within Rust.

imo the biggest bang for the buck is just having good `#!` support. Probably mid-year I expect to have a Pre-RFC up for single-file cargo packages. See https://github.com/epage/cargo-script-mvs/discussions/15.

A bigger effort is a batteries included, non-zero cost stdlib. I've started writing up my thoughts at https://github.com/ergo-rs/ergo.

For more background on why I think these are important, see https://epage.github.io/blog/2021/09/learning-rust/.

Would love feedback on these ideas and other ways to make Rust easy to use without sacrificing what makes Rust it is.

This is something I'm interested. Every time I write a bash or Python script, I think "why didn't I do this in Rust?". The first barrier is in the same line as your thoughts which is why I've been investigating the various cargo-script spin-offs and working towards an MVP for a Pre-RFC.

Something I've been thinking a lot about for Rust is what can and should a REPL experience be for a compiled language (ie what are reasonable compromises).

There seem to be two repls that haven't gotten much traction:

- https://github.com/google/evcxr/blob/main/evcxr_repl/README....

- https://github.com/sigmaSd/IRust

There have been little and big nits that have held me back from wanting to push these further, including

- Bad defaults (having to opt-in to panic handling)

- Command syntax feeling out of place and likely not beginner friendly

- Limits on variable preservation

- Lack of introspection (at least irust as `:type`)

So far I've been punting on wanting to improve this area by instead focusing on polishing up a rust script solution in the hopes of getting it merged: https://github.com/epage/cargo-script-mvs

rust-script is the most up-to-date version I could find. See https://github.com/epage/cargo-script-mvs/discussions/15

cargo-script has been forked or reimplemented several times.

cargo-script: I've done some initial analysis and recorded my thoughts on what cargo-script in Rust should look like. If people are interested in this or other individual / company on-boarding improvements, I'd love to talk!

Fully agree with this though I also feel there is room for experimentation and improvement in this area. I've previously blogged on this and have started researching cargo-script. Hopefully later I'll get to my standard-adjacent library.

Just a few minutes ago I learned about https://github.com/matklad/xshell and it looks nice!

For developer-oriented stuff, there's tools like xshell and cargo-xtask. For operator tasks that need to run in a deployed environment, it's not usually a big lift to add CLI subcommands to your binary. It's certainly more boilerplate and inertia than doing stuff in a live REPL, though, and sometimes difficult to recommend for truly one-off situations.

how was your experience with trying to use [xshell](https://github.com/matklad/xshell/) as a shell script replacement? was the boilerplate worth it?

Also xshell might be helpful here https://github.com/matklad/xshell

* time to compile whatever syn generated

I didn’t do a super thorough studies of things, but my impression is that 2, performance of syn itself, is rarely an issue. Most of the time it is 1) (and the associated problem of decreased build parallelism because half of the crates wait for syn to compile) and 3).

To get a feeling how costly a simple proc macro is, run this benchmark: https://github.com/matklad/xshell/blob/4e5090e9f79baeed1037b....

This is an API vulnerable to shell injection. I think it’s relatively important to design command-running libraries which don’t re-introduce the possibility of this error into Rust. The fix here is to ensure that the string is a compile-time string, and, preferably, even lex it at compile time. See xshell for an example of ergonomic and safe API here: https://github.com/matklad/xshell.

Note that “lexer level” proc macros, which don’t parse rust code, and which don’t generate a ton of Rust code, could be pretty light weight on compile times. Here’s a benchmark one can run to measure that: https://github.com/matklad/xshell/blob/master/tests/it/main.rs#L376