Fixes type bug where difficulty became an int if it exceeded the thresholds

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "fsrs"
-version = "4.1.1"
+version = "4.1.2"
 description = "Free Spaced Repetition Scheduler"
 readme = "README.md"
 authors = [{ name = "Jarrett Ye", email = "[email protected]" }]

src/fsrs/fsrs.py

@@ -663,7 +663,7 @@ def _initial_difficulty(self, rating: Rating) -> float:
         )
 
         # bound initial_difficulty between 1 and 10
-        initial_difficulty = min(max(initial_difficulty, 1), 10)
+        initial_difficulty = min(max(initial_difficulty, 1.0), 10.0)
 
         return initial_difficulty
 
@@ -704,7 +704,7 @@ def _mean_reversion(arg_1: float, arg_2: float) -> float:
         next_difficulty = _mean_reversion(arg_1=arg_1, arg_2=arg_2)
 
         # bound next_difficulty between 1 and 10
-        next_difficulty = min(max(next_difficulty, 1), 10)
+        next_difficulty = min(max(next_difficulty, 1.0), 10.0)
 
         return next_difficulty
 

tests/test_fsrs.py

@@ -55,6 +55,21 @@ def test_review_card(self):
             142,
         ]
 
+    def test_repeated_correct_reviews(self):
+        scheduler = Scheduler(enable_fuzzing=False)
+
+        card = Card()
+        review_datetimes = [
+            datetime(2022, 11, 29, 12, 30, 0, i, timezone.utc) for i in range(10)
+        ]
+
+        for review_datetime in review_datetimes:
+            card, _ = scheduler.review_card(
+                card=card, rating=Rating.Easy, review_datetime=review_datetime
+            )
+
+        assert card.difficulty == 1.0
+
     def test_memo_state(self):
         scheduler = Scheduler()