unpy

Backports Python typing stubs to earlier Python versions

[!IMPORTANT] This project is in the early stages of development; You probably shouldn't use it in production.

Installation

The unpy package is available as on PyPI, and can be installed with e.g.

pip install unpy

Usage

$ unpy --help
Usage: unpy [OPTIONS] SOURCE [OUTPUT]

Arguments:
  SOURCE    Path to the input .pyi file or '-' to read from stdin.  [required]
  [OUTPUT]  Path to the output .pyi file. Defaults to stdout.

Options:
  -V, --version        Show the version and exit
  -P, --python [3.11]  The minimum Python version that should be supported.
                       [default: 3.11]
  --help               Show this message and exit.

Features

• Python 3.13 => 3.12
  • PEP 742: typing.TypeIs => typing_extensions.TypeIs
  • PEP 705: typing.ReadOnly => typing_extensions.ReadOnly
  • PEP 702: warnings.deprecated => typing_extensions.deprecated
  • PEP 696: Backport PEP 695 type signatures i.f.f. it includes a type parameter with default
  • PEP 696: typing.NoDefault => typing_extensions.NoDefault
  • typing.get_protocol_members => typing_extensions.get_protocol_members
  • typing.is_protocol => typing_extensions.is_protocol
  • typing.is_protocol => typing_extensions.is_protocol
  • types.CapsuleType => typing_extensions.CapsuleType
  • nested typing.Final and typing.ClassVar
• Python 3.12 => 3.11
  • PEP 698: typing.override => typing_extensions.override
  • PEP 695: Backport generic functions
  • PEP 695: Backport generic classes
  • PEP 695: Backport generic protocols
  • PEP 695: type {} = ... => {}: TypeAlias = ... or
  • PEP 695: typing.TypeAliasType => typing_extensions.TypeAliasType
  • PEP 688: collections.abc.Buffer => typing_extensions.Buffer
  • PEP 688: inspect.BufferFlags => int
  • Backport subclasses of path.Path
• Python 3.11 => 3.10
  • PEP 681: typing.dataclass_transform => typing_extensions.dataclass_transform
  • PEP 680: tomllib => tomli
  • PEP 675: typing.LiteralString => typing_extensions.LiteralString
  • PEP 673: typing.Self => typing_extensions.Self
  • PEP 655: typing.[Not]Required => typing_extensions.[Not]Required
  • PEP 646: *Ts => typing_extensions.Unpack[Ts]
• Generated TypeVars
  • Prefix extracted TypeVars names with _
  • De-duplicate extracted TypeVars
  • Prevent TypeVar name clashes (rename or merge)
  • Infer variance of typing_extensions.TypeVar(..., infer_variance=True) whose name does not end with _contra/_in (contravariant=True) or _co/_out (covariant=True)
  • Convert default=Any to default={bound} or default=object
  • Remove bound=Any and bound=object
  • Importing TypeVar's (not recommended)
• Imports
  • Reuse existing from typing[_extensions] import {name} imports instead of adding new ones
  • Reuse from {module} import {name} as {alias} import aliases if present, e.g. from typing import TypeVar as TypeParam
  • Reuse import {module} as {alias} if present, e.g. import typing as tp
  • Support for custom typing modules (like [tool.ruff.lint.typing-modules])
  • Support for from typing[_extensions] import * (not recommended)
• Interface
  • Backport from stdin / to stdout
  • Backport a single .pyi file
  • Backport all .pyi files in package
  • Configuration options in pyproject.toml as [tools.unpy]
  • Project build tools
  • Configurable type-checker integration
  • Configurable post processing with e.g. ruff format
• Integration
  • File watcher
  • Pre-commit
  • VSCode extension
  • (based)mypy plugin
• Misc
  • .py support
  • Transform self parameters to be positional-only
  • Use None as the default return type
  • De-duplicate and flatten unions and literals
  • type[S] | type[T] => type[S | T]
• Extended syntax
  • Write _: True | 1 | "a" instead of _: Literal[True, 1, "a"]
  • Allow omitting @overload
  • Intersection types
  • Mapped types
  • Higher-kinded types