little-anyhow

little-anyhow is a vendorable error type with anyhow-style stack traces. This snippet helps you write low-dependency Rust binaries without your users noticing.

Install

little-anyhow is intentionally not published to crates.io -- that would defeat the point! It's not that the goal is to use dependencies without transitive dependencies, or dependencies that never require updates. The goal is to enable you to write ergonomic Rust binaries without any dependencies!

Consequently, little-anyhow should be vendored in your binary crate:

curl \
  --location \
  --create-dirs \
  --no-clobber \
  --output src/little_anyhow.rs \
  https://raw.githubusercontent.com/EricCrosson/little-anyhow/master/src/lib.rs

Use

Include the little_anyhow module in your main.rs:

mod little_anyhow;

little-anyhow is meant to be used in one place: the error type of the Result your main function returns. This converts any error your main function produces into a little_anyhow::Error, which provides human-readabale error messages for your users.

For example:

fn main() -> Result<(), little_anyhow::Error> {
    writeln!(
        io::stdout(),
        "You can create a little_anyhow::Error from any type implementing `std::error::Error`"
    )?;
    let simulated_error = std::fmt::Error;  // an easy-to-create error type
    Err(simulated_error)?
}

Error messages for errors without a source look like:

Error: error reading `Blocks.txt`

Error messages for errors with a source look like:

Error: error reading `Blocks.txt`

Caused by:
    0: invalid Blocks.txt data on line 223
    1: one end of range is not a valid hexidecimal integer
    2: invalid digit found in string

EricCrosson/little-anyhow

little-anyhow

Install

Use

Acknowledgments