mrrc 0.9.1

A Rust library for reading, writing, and manipulating MARC bibliographic records in ISO 2709 binary format
Documentation

MRRC

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A Rust library for reading, writing, and manipulating MARC bibliographic records, with Python bindings.

Note: This project was developed using agentic coding tools (amp and Claude) and uses beads_rust for agentic issue tracking. The package has not yet had extensive practical testing by humans and should be considered experimental.

Features

  • Reads and writes ISO 2709 (MARC21) binary format
  • Python bindings with pymarc-compatible API (minor differences documented)
  • Multiple serialization formats: JSON, MARCXML, MARCJSON, CSV, Dublin Core, MODS, BIBFRAME
  • MARC-8 and UTF-8 character encoding support
  • Rust-core parsing with GIL release for multi-threaded Python workloads — roughly 8× pymarc on per-record reads in a recent single-host comparison; see benchmarks for the current three-way figures

Installation

Python (3.10+):

pip install mrrc
# or with uv:
uv add mrrc

Rust:

cargo add mrrc

Example

Python:

from mrrc import MARCReader

# Pass filename directly for best performance (releases GIL)
for record in MARCReader("records.mrc"):
    print(record.title)

File paths use pure Rust I/O, releasing Python's GIL for multi-threaded workloads. See the threading guide for details.

Rust:

use mrrc::MarcReader;
use std::fs::File;

let file = File::open("records.mrc")?;
let mut reader = MarcReader::new(file);
while let Some(record) = reader.read_record()? {
    if let Some(title) = record.title() {
        println!("{}", title);
    }
}

Documentation

Format Support

Format Read Write
ISO 2709 Yes Yes
JSON Yes Yes
MARCJSON Yes Yes
MARCXML Yes Yes
CSV - Yes
Dublin Core - Yes
MODS Yes Yes
BIBFRAME Yes Yes

CSV and Dublin Core are write-only: both are lossy exports of a MARC record, so mrrc emits them but does not read them back. Bring your own reader if you need to import such data into MARC.

Full format reference

Platforms

Pre-built Python wheels are available for:

Platform Architectures
Linux x86_64, aarch64, i686
macOS x86_64 (Intel), arm64 (Apple Silicon)
Windows x64

Status

Experimental. The Python API aims for pymarc compatibility but has some differences; see the migration guide. Rust APIs may change between minor versions.

Roadmap

Version 0.9.1 is suitable for testing but remains experimental. Before a 1.0 release, we plan to complete:

  1. Real-world data testing — Validate against large-scale MARC datasets from LOC, Internet Archive, and other sources to discover edge cases
  2. Code review — Thorough review of the codebase, particularly the Rust core and PyO3 bindings
  3. Performance analysis — Profile with production workloads, optimize bottlenecks, and update benchmark documentation

Contributing

Contributions are welcome — see the contributing guide for setup, testing, and pull request instructions. To report a security vulnerability, see the security policy.

License

MIT

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