---
id: niltype
version: "1.0.2"
license: MIT
license_treatment: permissive
maintenance: dormant
---

# niltype — A singleton Nil object to represent missing values when None is a valid data value

License: permissive · Maintenance: dormant · Downloads: 100.1K/mo

## What it is and what it does

NilType provides a `Nil` singleton—a distinct sentinel value for representing the absence of data when `None` itself is a meaningful value in your data model. This solves a real problem in Python: when your domain allows `None` as a valid entry (e.g., a database field that can legitimately store null), you need a separate marker to mean 'no value provided' or 'undefined'. The package exports `Nil` for identity checks and a `Nilable` type alias for type annotations.

The typical use case is function signatures where you want to distinguish between an explicit `None` argument and no argument at all. For example, a `get()` function can use `Nil` as its default parameter value, then check `if default is not Nil` to know whether the caller passed something. The package is minimal—no dependencies, pure Python, and typed—making it a lightweight addition to any codebase that needs this pattern.

Use it for:

- Default function parameters: distinguish between an explicit `None` and an unspecified argument using `Nil` as the default.
- Data model fields: represent missing or undefined values in classes or dataclasses where `None` is a valid stored value.
- Optional configuration: mark configuration values as explicitly unset (Nil) versus set to None or a default.
- Type-hinted optional values: use `Nilable[T]` in function signatures to document that a value can be a type or Nil.
- Sentinel-based control flow: use identity checks (`is Nil`) to branch on whether a value was explicitly provided.

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

Provides a `Nil` singleton object to represent missing or undefined values in situations where `None` is itself a valid data value and cannot be used as a sentinel.

Yes, if you have a codebase where `None` is a valid data value and you need a distinct sentinel. The package is tiny, has no dependencies, is MIT-licensed, and solves a real semantic problem. Dormant maintenance is not a concern for a single-purpose utility with no external dependencies. Install it if the pattern fits your domain; skip it if you can use a different sentinel (e.g., a custom class) or if `None` is always sufficient.

## Install

pip install niltype
uv add niltype
poetry add niltype

## Installing niltype

Before you install: Low friction: pure Python wheel with no runtime dependencies. Maintenance is dormant—last commit was 2024-09-21 and no activity since, though the repository remains open and the package is typed.

License in practice: MIT license (permissive) places no restrictions on use, modification, or redistribution in commercial or private projects.

Quickstart:

pip install niltype

from niltype import Nil

if x is Nil:
    print("x is missing")

Verify before relying:

- Whether Nil works correctly with type checkers (mypy, pyright) beyond the Nilable type alias provided
- Performance characteristics when used in tight loops or large data structures
- Compatibility with pickle, dataclass, or other serialization frameworks

## Package facts

- License: MIT (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: dormant
- Downloads: 100.1K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

sentinel value for missing data, nil object python, distinguish none from missing, null placeholder when none is valid, optional value without overloading none, missing data representation, sentinel-value, type-hints

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