typing: bind recursive insertion sort to Comparable protocol

- insert_next was missing its TypeVar bound (Pyright: '<' operator invalid on T)
- Protocol __lt__ takes object, not Any; order check now relies on __lt__ only
- doctests: floats+ints mix, mixed [1, 'a'] raises TypeError

Part of #15234

Author: Silverbullets1

sorts/recursive_insertion_sort.py

@@ -5,17 +5,17 @@
 from __future__ import annotations
 
 from collections.abc import MutableSequence
-from typing import Any, Protocol, TypeVar
+from typing import Protocol, TypeVar
 
 
 class Comparable(Protocol):
-    def __lt__(self, other: Any, /) -> bool: ...
+    def __lt__(self, other: object, /) -> bool: ...
 
 
 T = TypeVar("T", bound=Comparable)
 
 
-def rec_insertion_sort[T](collection: MutableSequence[T], n: int) -> None:
+def rec_insertion_sort[T: Comparable](collection: MutableSequence[T], n: int) -> None:
     """
     Given a collection of comparable elements and its length, sorts the
     collection in place in ascending order.
@@ -42,6 +42,17 @@ def rec_insertion_sort[T](collection: MutableSequence[T], n: int) -> None:
     >>> rec_insertion_sort(col, len(col))
     >>> col
     ['a', 'b', 'c', 'd', 'e']
+
+    >>> col = [2.5, -1, 0.0, 1]
+    >>> rec_insertion_sort(col, len(col))
+    >>> col
+    [-1, 0.0, 1, 2.5]
+
+    >>> col = [1, "a"]
+    >>> rec_insertion_sort(col, len(col))
+    Traceback (most recent call last):
+        ...
+    TypeError: '<' not supported between instances of 'str' and 'int'
     """
     # Checks if the entire collection has been sorted
     if len(collection) <= 1 or n <= 1:
@@ -51,7 +62,7 @@ def rec_insertion_sort[T](collection: MutableSequence[T], n: int) -> None:
     rec_insertion_sort(collection, n - 1)
 
 
-def insert_next[T](collection: MutableSequence[T], index: int) -> None:
+def insert_next[T: Comparable](collection: MutableSequence[T], index: int) -> None:
     """
     Inserts the '(index-1)th' element into place
 
@@ -71,7 +82,8 @@ def insert_next[T](collection: MutableSequence[T], index: int) -> None:
     []
     """
     # Checks order between adjacent elements
-    if index >= len(collection) or collection[index - 1] <= collection[index]:
+    # Only relies on ``__lt__`` so any Comparable works
+    if index >= len(collection) or not collection[index] < collection[index - 1]:
         return
 
     # Swaps adjacent elements since they are not in ascending order