fionn 0.1.0

Fast JSON library with SIMD acceleration - drop-in orjson replacement + extended features

fionn-py

Python bindings for fionn - Fast JSON library with SIMD acceleration.

Features

• Drop-in orjson replacement: import fionn works like import orjson
• ISONL streaming: 11.9x faster than fastest JSON parser (sonic-rs)
• JSONL streaming: Schema-filtered parsing with batch processing
• Multi-format: YAML, TOML, CSV, ISON, TOON parsing
• Extended ops: Gron, Diff/Patch, CRDT, Tape API

Installation

# Using uv (recommended)
uv pip install fionn

# Using pip
pip install fionn

Quick Start

orjson-compatible API

import fionn

# Parse JSON
data = fionn.loads(b'{"name": "Alice", "age": 30}')

# Serialize JSON
output = fionn.dumps(data, option=fionn.OPT_INDENT_2)

ISONL Streaming (11.9x faster)

import fionn.ext as fx

# Read ISONL (schema-embedded, zero inference overhead)
for batch in fx.IsonlReader("data.isonl"):
    for record in batch:
        process(record)

# Convert JSONL to ISONL for 11.9x speedup on repeated reads
fx.jsonl_to_isonl("input.jsonl", "output.isonl", table="events", infer_schema=True)

Performance

Operation	Baseline	fionn	Speedup
JSON loads	orjson	match	1x
JSONL streaming	sonic-rs	match	1x
ISONL streaming	sonic-rs	11.9x faster	11.9x

Development

# Install dev dependencies
uv sync --dev

# Build
maturin develop

# Test
pytest

# Lint
ruff check .

# Type check
mypy .

License

MIT OR Apache-2.0