PEP 724: Add the Rationale section (#3447)

python · Sep 23, 2023 · a159a9a · a159a9a
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diff --git a/peps/pep-0724.rst b/peps/pep-0724.rst
@@ -83,6 +83,19 @@ The following code sample demonstrates both of these limitations.
 return ``TypeGuard`` type was not a subtype of the input type. Refer to
 :pep:`647` for examples.
 
+Rationale
+=========
+
+There are a number of issues where a stricter ``TypeGuard`` would have
+been a solution:
+
+* `Python typing issue - TypeGuard doesn't intersect like isinstance <https://github.com/python/typing/issues/1351>`__
+* `Pyright issue - TypeGuard not eliminating possibility on branch <https://github.com/microsoft/pyright/issues/3450>`__
+* `Pyright issue - Type narrowing for Literal doesn't work <https://github.com/microsoft/pyright/issues/3466>`__
+* `Mypy issue - TypeGuard is incompatible with exhaustive check <https://github.com/python/mypy/issues/15305>`__
+* `Mypy issue - Incorrect type narrowing for inspect.isawaitable <https://github.com/python/mypy/issues/15520>`__
+* `Typeshed issue - asyncio.iscoroutinefunction is not a TypeGuard <https://github.com/python/typeshed/issues/8009>`__
+
 
 Specification
 =============