[3.12] Link to the Python type system specification (GH-117400) (#117448)

Co-authored-by: Shantanu <12621235+hauntsaninja@users.noreply.github.com>

Author: miss-islington

Doc/library/typing.rst

@@ -23,27 +23,25 @@
 
 --------------
 
-This module provides runtime support for type hints. For the original
-specification of the typing system, see :pep:`484`. For a simplified
-introduction to type hints, see :pep:`483`.
+This module provides runtime support for type hints.
 
+Consider the function below::
 
-The function below takes and returns a string and is annotated as follows::
+   def moon_weight(earth_weight: float) -> str:
+       return f'On the moon, you would weigh {earth_weight * 0.166} kilograms.'
 
-   def greeting(name: str) -> str:
-       return 'Hello ' + name
+The function ``moon_weight`` takes an argument expected to be an instance of :class:`float`,
+as indicated by the *type hint* ``earth_weight: float``. The function is expected to
+return an instance of :class:`str`, as indicated by the ``-> str`` hint.
 
-In the function ``greeting``, the argument ``name`` is expected to be of type
-:class:`str` and the return type :class:`str`. Subtypes are accepted as
-arguments.
+While type hints can be simple classes like :class:`float` or :class:`str`,
+they can also be more complex. The :mod:`typing` module provides a vocabulary of
+more advanced type hints.
 
 New features are frequently added to the ``typing`` module.
 The `typing_extensions <https://pypi.org/project/typing-extensions/>`_ package
 provides backports of these new features to older versions of Python.
 
-For a summary of deprecated features and a deprecation timeline, please see
-`Deprecation Timeline of Major Features`_.
-
 .. seealso::
 
    `"Typing cheat sheet" <https://mypy.readthedocs.io/en/stable/cheat_sheet_py3.html>`_
@@ -61,67 +59,11 @@ For a summary of deprecated features and a deprecation timeline, please see
 
 .. _relevant-peps:
 
-Relevant PEPs
-=============
-
-Since the initial introduction of type hints in :pep:`484` and :pep:`483`, a
-number of PEPs have modified and enhanced Python's framework for type
-annotations:
-
-.. raw:: html
-
-   <details>
-   <summary><a style="cursor:pointer;">The full list of PEPs</a></summary>
-
-* :pep:`526`: Syntax for Variable Annotations
-     *Introducing* syntax for annotating variables outside of function
-     definitions, and :data:`ClassVar`
-* :pep:`544`: Protocols: Structural subtyping (static duck typing)
-     *Introducing* :class:`Protocol` and the
-     :func:`@runtime_checkable<runtime_checkable>` decorator
-* :pep:`585`: Type Hinting Generics In Standard Collections
-     *Introducing* :class:`types.GenericAlias` and the ability to use standard
-     library classes as :ref:`generic types<types-genericalias>`
-* :pep:`586`: Literal Types
-     *Introducing* :data:`Literal`
-* :pep:`589`: TypedDict: Type Hints for Dictionaries with a Fixed Set of Keys
-     *Introducing* :class:`TypedDict`
-* :pep:`591`: Adding a final qualifier to typing
-     *Introducing* :data:`Final` and the :func:`@final<final>` decorator
-* :pep:`593`: Flexible function and variable annotations
-     *Introducing* :data:`Annotated`
-* :pep:`604`: Allow writing union types as ``X | Y``
-     *Introducing* :data:`types.UnionType` and the ability to use
-     the binary-or operator ``|`` to signify a
-     :ref:`union of types<types-union>`
-* :pep:`612`: Parameter Specification Variables
-     *Introducing* :class:`ParamSpec` and :data:`Concatenate`
-* :pep:`613`: Explicit Type Aliases
-     *Introducing* :data:`TypeAlias`
-* :pep:`646`: Variadic Generics
-     *Introducing* :data:`TypeVarTuple`
-* :pep:`647`: User-Defined Type Guards
-     *Introducing* :data:`TypeGuard`
-* :pep:`655`: Marking individual TypedDict items as required or potentially missing
-     *Introducing* :data:`Required` and :data:`NotRequired`
-* :pep:`673`: Self type
-    *Introducing* :data:`Self`
-* :pep:`675`: Arbitrary Literal String Type
-    *Introducing* :data:`LiteralString`
-* :pep:`681`: Data Class Transforms
-    *Introducing* the :func:`@dataclass_transform<dataclass_transform>` decorator
-* :pep:`692`: Using ``TypedDict`` for more precise ``**kwargs`` typing
-    *Introducing* a new way of typing ``**kwargs`` with :data:`Unpack` and
-    :data:`TypedDict`
-* :pep:`695`: Type Parameter Syntax
-    *Introducing* builtin syntax for creating generic functions, classes, and type aliases.
-* :pep:`698`: Adding an override decorator to typing
-    *Introducing* the :func:`@override<override>` decorator
-
-.. raw:: html
-
-   </details>
-   <br>
+Specification for the Python Type System
+========================================
+
+The canonical, up-to-date specification of the Python type system can be
+found at `"Specification for the Python type system" <https://typing.readthedocs.io/en/latest/spec/index.html>`_.
 
 .. _type-aliases: