v0.36.5: Duration arithmetic support

Duration enum now supports multiplication, division, and addition
so expressions like `Duration.WHOLE * 2` work instead of raising TypeError.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 All notable changes to PyTheory are documented here.
 
+## 0.36.5
+
+- **Duration arithmetic** — `Duration.WHOLE * 2`, `Duration.HALF + Duration.QUARTER`,
+  division, and reverse multiply all work now (previously raised TypeError)
+
 ## 0.36.3
 
 - **`Part.hold()`** — polyphonic overlap on a single part. Add notes

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "pytheory"
-version = "0.36.4"
+version = "0.36.5"
 description = "Music Theory for Humans"
 readme = "README.md"
 license = "MIT"

pytheory/__init__.py

@@ -1,6 +1,6 @@
 """PyTheory: Music Theory for Humans."""
 
-__version__ = "0.36.4"
+__version__ = "0.36.5"
 
 from .tones import Tone, Interval
 from .systems import System, SYSTEMS, TET

pytheory/rhythm.py

@@ -388,6 +388,24 @@ class Duration(Enum):
     DOTTED_QUARTER = 1.5
     TRIPLET_QUARTER = 2 / 3
 
+    # Arithmetic — lets you write ``Duration.WHOLE * 2`` → 8.0 beats.
+    def __mul__(self, other):
+        return self.value * other
+
+    def __rmul__(self, other):
+        return self.value * other
+
+    def __truediv__(self, other):
+        return self.value / other
+
+    def __add__(self, other):
+        if isinstance(other, Duration):
+            return self.value + other.value
+        return self.value + other
+
+    def __radd__(self, other):
+        return other + self.value
+
 
 class TimeSignature:
     """A musical time signature like 4/4 or 6/8."""

test_pytheory.py

@@ -4869,6 +4869,19 @@ def test_duration_values():
     assert abs(Duration.TRIPLET_QUARTER.value - 2 / 3) < 1e-9
 
 
+def test_duration_arithmetic():
+    # Multiplication
+    assert Duration.WHOLE * 2 == 8.0
+    assert 2 * Duration.HALF == 4.0
+    assert Duration.QUARTER * 3 == 3.0
+    # Division
+    assert Duration.WHOLE / 2 == 2.0
+    # Addition
+    assert Duration.HALF + Duration.QUARTER == 3.0
+    assert Duration.HALF + 1.0 == 3.0
+    assert 1.0 + Duration.HALF == 3.0
+
+
 def test_time_signature_from_string_4_4():
     ts = TimeSignature.from_string("4/4")
     assert ts.beats == 4

uv.lock

@@ -698,7 +698,7 @@ wheels = [
 
 [[package]]
 name = "pytheory"
-version = "0.36.4"
+version = "0.36.5"
 source = { editable = "." }
 dependencies = [
     { name = "numeral" },