Verple

Verple is a ridiculously strict and ultra-conservative universal version format, comparator, serializer, and protocol.

Design Goals

• 🔒 Ultra-conservative equality: versions are considered different if any field differs (release, prerelease, postrelease, devrelease, local).
• ⚖ Strict conservative ordering: ordering is only permitted when local metadata matches exactly; otherwise ordering raises ValueError to avoid ambiguity.
• 🔎 Multi-standard input support: parses version strings from PEP 440, SemVer, Canonical, and Calendar Versioning (CalVer).
• 🔁 Canonical serialization: provides fully reversible serialization via to_canonical_string() and parsing via from_canonical_string().
• 🧮 Hashable and set-safe: fully hashable and safe for use in sets and dictionaries, with hashes consistent with strict equality.
• 📦 JSON-LD serialization: supports semantic serialization with provenance (sourceFormat and sourceInput fields).
• 🔐 Versioned deserialization protocol: fully versioned serialization model allowing future-safe protocol evolution.
• 📚 Use Case Domains: reproducible builds, registries, deployment pipelines, archival systems, provenance tracking, scientific reproducibility.

Supported Python Versions

• Python >= 3.10

Installation

pip install verple

Example Usage

from verple import Verple

# Parse version string
v1 = Verple.parse("1.2.3a1.post2.dev3+build99")
print(v1.to_canonical_string())  # 1.2.3-a1.post2.dev3+build99

# Strict equality
v2 = Verple.parse("1.2.3a1.post2.dev3+build99")
assert v1 == v2

# Hashable and set-safe
versions = {v1, v2}
assert len(versions) == 1

# Conservative ordering (only if local metadata matches)
v3 = Verple.parse("1.2.4+build99")
assert v1 < v3

# JSON-LD serialization
jsonld = v1.to_jsonld()
v1_roundtrip = Verple.from_jsonld(jsonld)
assert v1 == v1_roundtrip

Canonical Serialization Format

Verple canonical strings follow this grammar:

<release>[-<prerelease>][.post<N>][.dev<N>][+<local>]

Example:

• 1.2.3-a1.post2.dev3+build99

JSON-LD Serialization Format

Verple also supports semantic serialization:

{
  "@context": "https://gitlab.com/willynilly/verple/-/raw/main/src/verple/context/v1.0.0.jsonld",
  "@type": "Verple",
  "verple": "1.0.0",
  "sourceFormat": "pep440",
  "sourceInput": "1.2.3a1.post2.dev3+build99",
  "release": [1, 2, 3],
  "prerelease": ["a", 1],
  "postrelease": 2,
  "devrelease": 3,
  "local": "build99"
}

This allows full provenance and schema evolution.

Tests

This project uses pytest:

pytest tests/

Protocol Semantics

Normalization

Verple normalizes versions into a fully structured model with the following fields:

• release: tuple of integers (major, minor, patch, or calendar parts)
• prerelease: tuple of (label: str, num: int) or None
• postrelease: integer or None
• devrelease: integer or None
• local: string or None
• sourceInput: original version string
• sourceFormat: the parsed format (pep440, semver, canonical, calver)

All formats (PEP 440, SemVer, Canonical, CalVer) are converted into this internal structure.

Equality Algorithm

Two versions are equal if and only if all of the following fields are equal:

• release
• prerelease
• postrelease
• devrelease
• local

Fields are compared strictly; any difference implies inequality.

Ordering Algorithm

Ordering is permitted only if both versions have identical local metadata. If local differs, ordering is refused.

If allowed, versions are compared using the tuple:

(
  release,
  prerelease_key(prerelease),
  postrelease or -1,
  devrelease or infinity
)

Where:

• prerelease_key(None) → (infinity,) (normal releases sort after prereleases)
• prerelease_key((label, num)) → (label, num) (string then numeric comparison)

The algorithm aligns with PEP 440 precedence where applicable.

Canonical Form Algorithm

Serialization via to_canonical_string() reconstructs the version string as:

<release>[-<prerelease>][.post<N>][.dev<N>][+<local>]

Fields that are None are omitted.

JSON-LD Serialization

The full semantic model is serialized as JSON-LD, including provenance fields sourceFormat and sourceInput for full reproducibility.

Field Definitions

The following fields are used throughout Verple's internal model, canonical serialization, and JSON-LD serialization:

Field	Type	Meaning
release	tuple of int	Core version numbers: major.minor.patch or calendar parts
prerelease	tuple (str, int) or None	Pre-release stage (alpha, beta, rc, etc.) and stage number
postrelease	int or None	Post-release revision applied after final release
devrelease	int or None	Development release version for pre-release internal builds
local	str or None	Local build metadata identifier (build info, git hash, etc.)
sourceInput	str	The original version string provided as input
sourceFormat	str	The detected format: pep440, semver, canonical, or calver
verple	str	Serialization format version (e.g. "1.0.0")
@context	URL	JSON-LD context URL defining linked data vocabulary
@type	str	Always "Verple"

Conceptual Definitions

• release: The main numeric version (e.g. 1.2.3), structured as Major.Minor.Patch (SemVer, PEP 440) or Year.Month.[Day] (CalVer).

• prerelease: A pre-final release marker such as alpha, beta, or rc, optionally followed by a stage number (e.g. rc1).

• postrelease: Identifies patches or hotfixes applied after a final release (.postN).

• devrelease: Development snapshots issued before formal releases (.devN), typically for internal or unstable builds.

• local: Build metadata or local identifiers following +build semantics, capturing build environment or other internal state.

• sourceInput: The raw version string provided by the caller.

• sourceFormat: Indicates which parser was used to interpret the input (pep440, semver, canonical, calver).

• verple: The version of the Verple serialization protocol used to encode the JSON-LD document.

• @context / @type: JSON-LD linked data metadata used to enable semantic parsing of Verple objects.

License

Apache 2.0

Author

• Will Riley
• Co-developed with ChatGPT-4o during protocol design.