ABC notation export via Score.to_abc() — v0.41.0

New method converts scores to ABC notation with support for multi-voice,
chords, rests, accidentals, and all durations. Pass html=True for a
self-contained HTML page with abcjs sheet music rendering.

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

CHANGELOG.md

@@ -2,6 +2,13 @@
 
 All notable changes to PyTheory are documented here.
 
+## 0.41.0
+
+- **ABC notation export** — `Score.to_abc()` converts scores to ABC notation
+  strings. Supports multi-voice scores (via `V:` directives), chords, rests,
+  accidentals, and all standard durations. Pass `html=True` to get a
+  self-contained HTML page that renders sheet music in the browser via abcjs.
+
 ## 0.40.9
 
 - **Mellotron synth** — tape-replay keyboard with wow/flutter, tape saturation,

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "pytheory"
-version = "0.40.9"
+version = "0.41.0"
 description = "Music Theory for Humans"
 readme = "README.md"
 license = "MIT"

pytheory/__init__.py

@@ -1,6 +1,6 @@
 """PyTheory: Music Theory for Humans."""
 
-__version__ = "0.40.9"
+__version__ = "0.41.0"
 
 from .tones import Tone, Interval
 from .systems import System, SYSTEMS, TET

pytheory/rhythm.py

@@ -4463,11 +4463,13 @@ class Score:
 
         return f"{abc_acc}{note_char}{oct_str}"
 
-    def _notes_to_abc(self, notes, default_unit, ts):
+    def _notes_to_abc(self, notes, default_unit, ts,
+                      bars_per_line=4):
         """Convert a list of Note objects to an ABC body string."""
         beats_per_measure = ts.beats_per_measure
-        parts = []
+        tokens = []
         beat_in_measure = 0.0
+        measure_count = 0
 
         for note in notes:
             beats = note.duration.value
@@ -4506,16 +4508,20 @@ class Score:
                 frac = Fraction(multiplier).limit_denominator(16)
                 dur_str = f"{frac.numerator}/{frac.denominator}"
 
-            parts.append(f"{abc_note}{dur_str}")
+            tokens.append(f"{abc_note}{dur_str}")
 
             beat_in_measure += beats
             if beat_in_measure >= beats_per_measure - 0.001:
-                parts.append("|")
+                measure_count += 1
+                if measure_count % bars_per_line == 0:
+                    tokens.append("|\n")
+                else:
+                    tokens.append("|")
                 beat_in_measure -= beats_per_measure
 
-        body = " ".join(parts)
+        body = " ".join(tokens)
         # Clean up trailing/double barlines
-        body = body.replace("| |", "|").rstrip("| ").rstrip()
+        body = body.replace("| |", "|").rstrip("| \n").rstrip()
         if not body.endswith("|"):
             body += " |"
         return body

uv.lock

@@ -690,7 +690,7 @@ wheels = [
 
 [[package]]
 name = "pytheory"
-version = "0.40.9"
+version = "0.41.0"
 source = { editable = "." }
 dependencies = [
     { name = "rich" },