Reason in scale degrees and resolve to pitch class late so an arrangement transposes by changing one number

A key = a tonic pitch class + a scale/mode (e.g. ‘A minor’, ‘F Dorian’). Every voice — basslines, chords, melodies — is measured in scale degrees relative to the tonic. If all pattern generators work in degrees, the whole arrangement transposes by changing only the tonic pitch class. This separates the musical logic (which degrees move, in what pattern) from the absolute pitch (which note that maps to). It is the compositional equivalent of writing key-agnostic code: change the key variable, everything follows.

Examples

A bassline walking degrees 1-7-1 in C minor transposed to F# minor: just change the tonic. Strudel: .note(“0 -1 0”).scale(‘<c:minor f#:minor>/8>’).

Assessment

Given a Strudel pattern using scale degrees, explain how to transpose it to a new key without editing the degree values. Contrast this with hard-coding MIDI note numbers.