yeptris — YAML for Python at libleptris speed
An FFI-based (no C extension) YAML library over libyeptris — the YAML counterpart of libleptris. PyYAML-compatible semantics, one shared library, zero compilation at install.
Part of the yeptris program: the best (multiple dimensions) YAML/JSON parser/builder ever — conformance, performance, safety/hardening, API surfaces, transport correctness, and trust, held simultaneously, in C, Ruby, Rust, and JS. This binding carries the PyYAML-compatible surface plus CBOR, tracking every libyeptris release in lockstep. The achievement program lives in the engine's PLAN.md ("The best-ever program").
Install (development)
# the sibling C checkout: ~/src/leptris/yeptris
cmake -B build -S . -DCMAKE_BUILD_TYPE=Release -DYEPTRIS_BUILD_SHARED=ON
cmake --build build
cd ~/src/leptris/yeptris-py
YEPTRIS_LIB_PATH=../yeptris/build/src/libyeptris.dylib python3 -m pytest
Without YEPTRIS_LIB_PATH the loader falls back to a vendored
yeptris/_platform/<tag>/ copy, then to the sibling checkout's
build directory. Any libyeptris.{so,dylib,dll} path works.
Usage
import yeptris
from yeptris import yaml # PyYAML-compatible surface
yaml.safe_load("name: yeptris\nrating: 10\n")
# {'name': 'yeptris', 'rating': 10}
yaml.safe_load_all("--- 1\n--- two\n") # [1, 'two']
yaml.safe_dump({"b": 2, "a": [1, "x"]}) # 'a:\n - 1\n - x\nb: 2\n'
yeptris.load("k: v") # the neutral surface
yeptris.dump({"k": [1, 2]})
Typing follows PyYAML's SafeLoader (YAML 1.1 implicit typing):
yes/no/on/off booleans, 0x/leading-0/0b/sexagesimal integers,
dot-required floats, timestamps with offsets, merge keys, anchor
identity. Every deliberate divergence is pinned by a test.
Design
One parse, one bulk drain: the record array and string arena are
read in two FFI calls, then a pure-Python walk over the unpacked
records — the FFI tax is O(1) per document, never per event (the
same seam yeptris-ruby rides). The 36-byte record layout is
ABI-pinned in the C header and mirrored in _ffi.py.
Performance
python3 bench.py — same-process comparison against PyYAML (pure)
and CSafeLoader/CDumper (libyaml C extensions):
- load: 28-39x PyYAML pure, 3.8-6.1x CSafeLoader
- dump: ~1.7x PyYAML pure, ~2x behind CDumper (which walks the
tree entirely in C — a no-C-extension design's ceiling is the
Python walk itself; the tree raises through ONE
yeptris_document_buildcall)
Both directions are O(chunks) in FFI calls: loads drain records in two calls, dumps build through one flat entry array.
JSON (strict RFC 8259) — yeptris.json
yeptris.json.loads is json.loads-compatible (values, rejects,
types, json.JSONDecodeError — including stdlib's default NaN/
Infinity constant quirk) with two engines behind one contract:
- native — the opt-in extension
ext/yeptris_native.c: a fused scan-kernel descent over libyeptris (the same shape as the Ruby binding's materializer), with a 1024-slot interned-free key cache. Build it withYEPTRIS_LIB_PATH+YEPTRIS_SRCset (python3 setup.py build_ext --inplace); CI builds and gates it. - strict-ffi — the default pure path:
yeptris_parse_jsonis the validator gate, then the columnar value walk converts under JSON rules. No C extension, correct everywhere.
benchmark/json_profile.py is the referee (order-alternating
interleave vs the C scanner): the native engine runs 0.67-0.87x
json.loads mean (83-85% head-to-head) on the 144 KB reference
corpus; shape decomposition: int arrays 0.63x, float arrays 0.77x,
long strings 0.85x, unique-key maps 0.95x. The previous pure walk
was ~15x BEHIND — the fused materializer is the entire gap.
Installing the native JSON engine (platform wheels)
pip install yeptris on macOS (arm64) and manylinux (x86_64)
installs platform wheels that vendor libyeptris and the native
JSON materializer (abi3 — one wheel per platform serves CPython
3.9+): zero compiler, zero env vars, yeptris.json.engine() is
native out of the box. Every wheel is release-smoked in a clean
venv before publish. Other platforms install the pure package (the
strict-ffi JSON engine + YAML via libyeptris through the
YEPTRIS_LIB_PATH ladder); building the extension from source is
YEPTRIS_LIB_PATH=... YEPTRIS_SRC=... python3 setup.py build_ext --inplace.
1 maintainer
Metadata
1 maintainer
Release files for yeptris 0.6.35.2
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Source distribution (sdist)
| File | Size | Uploaded | Provenance | |
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| yeptris-0.6.35.2.tar.gz | 345.9 kB | With provenance | Details |
Built distributions (wheels)
| File | Reset | |||
|---|---|---|---|---|
| yeptris-0.6.35.2-py3-none-any.whl | Python 3 | none | any | Details |
| yeptris-0.6.35.2-cp39-abi3-win_arm64.whl | CPython 3.9 | abi3 | Windows ARM64 | Details |
| yeptris-0.6.35.2-cp39-abi3-win_amd64.whl | CPython 3.9 | abi3 | Windows x86-64 | Details |
| yeptris-0.6.35.2-cp39-abi3-musllinux_1_2_x86_64.whl | CPython 3.9 | abi3 | Linux musl 1.2+ x86-64 | Details |
| yeptris-0.6.35.2-cp39-abi3-musllinux_1_2_aarch64.whl | CPython 3.9 | abi3 | Linux musl 1.2+ ARM64 | Details |
| yeptris-0.6.35.2-cp39-abi3-manylinux2014_x86_64.manylinux_2_17_x86_64.whl | CPython 3.9 | abi3 | Linux glibc 2.17+ x86-64 | Details |
| yeptris-0.6.35.2-cp39-abi3-manylinux2014_aarch64.manylinux_2_17_aarch64.whl | CPython 3.9 | abi3 | Linux glibc 2.17+ ARM64 | Details |
| yeptris-0.6.35.2-cp39-abi3-macosx_11_0_x86_64.whl | CPython 3.9 | abi3 | macOS 11.0+ x86-64 | Details |
| yeptris-0.6.35.2-cp39-abi3-macosx_11_0_arm64.whl | CPython 3.9 | abi3 | macOS 11.0+ ARM64 | Details |
Total release size: 9.5 MB
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