Pylits

pylits is a high-performance, deterministic serialization format for pure Python literals.

It provides extremely fast and reliable encoding/decoding while intentionally supporting only safe literal types, making it suitable for:

• Storing data in files (safely than eval())
• Transforming your DB into dynamic typed structures with support for lists and dictionaries
• Hashing

Key Features

• ⚡ Very fast — minimal parsing overhead compared to JSON-like formats
• 🔒 Safe by design — supports only pure Python literals
• 🎯 Deterministic — identical data always produces identical encoded output
• 🧩 Zero dependencies — pure Python implementation
• 🔁 Lossless round-trip — decode(encode(x)) == x

Supported Types

pylits works strictly with Python literal structures:

SupportedTypes = (
    bool
    | int
    | float
    | str
    | list["SupportedTypes"]
    | tuple["SupportedTypes", ...]
    | set["SupportedTypes"]
    | dict["SupportedTypes", "SupportedTypes"]
    | None
)

Anything outside this set is intentionally not supported.

Installation

pip install pylits

Quick Start

import pylits

data = [1, "2", True, (None, {"Pylits": 21})]

encoded = pylits.encode(data)
decoded = pylits.decode(encoded)

assert decoded == data

Examples

Lists

pylits.encode([1, "2"])
# "2l1i11s2"

pylits.decode("2l1i11s2")
# [1, "2"]

Strings

pylits.encode(["A", "AB", "ABC", "ABCD"])
# "4l1sA2sAB3sABC4sABCD"

Booleans

pylits.encode([True, False])
# "2l1bT1bF"

Deterministic Encoding

A modified internal encoder guarantees stable output even when:

• dictionary key order differs
• set element order differs

This makes pylits suitable for hashing.

License

MIT License
Copyright (c) 2026 Romashka