add tranpose method

repl/src/tonal.ts

@@ -0,0 +1,15 @@
+import { Note, Interval } from '@tonaljs/tonal';
+import { Pattern as _Pattern } from '../../strudel.mjs';
+
+const Pattern = _Pattern as any;
+
+Pattern.prototype._transpose = function (intervalOrSemitones: string | number) {
+  const interval = !isNaN(Number(intervalOrSemitones))
+    ? Interval.fromSemitones(intervalOrSemitones as number)
+    : String(intervalOrSemitones);
+  return this.fmap((note) => Note.transpose(note, interval));
+};
+
+Pattern.prototype.transpose = function (intervalOrSemitones: string | number) {
+  return this._patternify(Pattern.prototype._transpose)(intervalOrSemitones);
+};