# Larpa: The **L**ousy **Ar**gument **Pa**rser.
A simple `#[derive]`-based command line argument parsing library.
## Goals
- Stay more lightweight than Clap, while providing many of its bells and whistles in an
easier-to-digest package with a simpler API.
- Provide built-in generation of `--help`/`--version` output.
- Build a well-designed, stable, intuitive API surface that I can proudly publish as 1.0.0.
## Non-Goals
- Handle all possible command-line interfaces.
- *Larpa* aims to handle all reasonable command-line interfaces that roughly adhere to the
[GNU CLI argument conventions], but not more than that.
- In particular, order-dependent named arguments or argument groups will probably never be
supported, as the `#[derive]`-based design isn't a good fit. Use something like [lexopt] instead.
- Dynamically constructing and modifying the accepted syntax of the command-line interface will
also likely never be supported. Use [Clap] instead.
- Handle weird/niche use cases like `#![no_std]` usage, or operating systems that are significantly
different from Unix or Windows.
[GNU CLI argument conventions]: https://sourceware.org/glibc/manual/2.42/html_mono/libc.html#Argument-Syntax
[lexopt]: https://github.com/blyxxyz/lexopt
[Clap]: https://github.com/clap-rs/clap
## Example
```rust
use larpa::Command;
use larpa::types::Verbosity;
use std::path::PathBuf;
#[derive(Command)]
struct Shredder {
/// Output more information.
#[larpa(name = ["-v", "--verbose"], flag)]
verbosity: Verbosity,
/// Output less information.
#[larpa(name = ["-q", "--quiet"], flag, inverse_of = "verbosity")]
quiet: (),
/// The configuration file to use.
#[larpa(name = "--config")]
config: Option<PathBuf>,
/// The speed to run the shredder at (in RPM).
#[larpa(name = ["-s", "--speed"], default = "8000.0")]
speed: f64,
/// Path to the file to shred (or `-` to shred data from stdin).
file: PathBuf,
}
```