Stop nth after reading the requested item

CHANGELOG.rst

@@ -6,6 +6,7 @@ Changelog
 Unreleased
 ----------
 
+- Stop consuming iterables in ``nth`` once a nonnegative index has been reached.
 - Transliterate letters like ``ß``, ``æ``, ``ø`` and ``Ł`` in ``slugify`` through ``deburr`` instead of
   dropping them.
 - Search values in generic mappings with ``includes`` and respect the start offset.

src/pydash/arrays.py

@@ -1216,12 +1216,14 @@ def nth(array: t.Iterable[T], pos: int = 0) -> t.Union[T, None]:
 
     .. versionchanged:: VERSION
         Support iterables that are not sequences, such as generators and sets.
-        They previously returned ``None``.
+        For a nonnegative index, iteration stops once the requested element is found.
     """
     # pyd.get indexes by position, which needs a sequence. A mapping is left
     # alone because it is indexed by key rather than position, and realizing
     # one would look up its keys instead.
     if not isinstance(array, (Sequence, Mapping)):
+        if isinstance(pos, int) and pos >= 0:
+            return next((value for index, value in enumerate(array) if index == pos), None)
         array = list(array)
     return pyd.get(array, pos)
 

tests/test_arrays.py

@@ -705,6 +705,21 @@ def test_nth_with_non_sequence_iterables(factory, pos, expected):
     assert _.nth(factory(), pos) == expected
 
 
+@parametrize("pos", [0, 2])
+def test_nth_only_consumes_through_the_requested_position(pos):
+    def values():
+        yield from range(pos + 1)
+        pytest.fail("nth consumed an item after the requested position")
+
+    assert _.nth(values(), pos) == pos
+
+
+def test_nth_leaves_remaining_items_in_the_iterator():
+    values = iter([11, 22, 33, 44])
+    assert _.nth(values, 1) == 22
+    assert list(values) == [33, 44]
+
+
 @parametrize(
     "case,pos,expected",
     [({0: "x", 1: "y"}, 0, "x"), ({0: "x", 1: "y"}, 1, "y"), ({"a": 1}, 0, None)],