Chords

chords(beats, scale, progression)

Returns a ChordPattern that cycles through a Roman-numeral chord progression.

chords(beats: number, scale: ScalePattern, progression: string): ChordPattern

progression format

A comma-separated string of Roman numerals: 'I,IV,V,I'

Available Roman numerals

Uppercase letters produce diatonic triads. Lowercase is also accepted. The chord quality follows the scale’s diatonic rules automatically.

I II III IV V VI VII

Quality suffixes can be appended: maj min / m dim aug 7 maj7 min7 / m7 dim7 9

Example

const key  = scales(4, 'D4:minor')
const prog = chords(8, key, 'I,VII,VI,III')

// pass prog as the scale argument to cast()
yield cast(ep, prog, seq(4, '{0,2,4},~,~,~'), ctx)

~ or _ after a numeral holds the preceding chord for an extra step:

chords(4, key, 'I~~,V')       // I for 3 beats, V for 1
chords(4, key, 'Imaj7,IVmaj7,V7,I')

Octave shift

Append < (down) or > (up) to move all chord tones by one octave. Repeat the symbol for multiple octaves, or use <N> with a signed integer.

Syntax	Octaves	Example
IV<	−1	chords(4, key, 'I IV< V I')
IV>	+1	chords(4, key, 'I> IV V I')
IV<<	−2	bass-register voicing
IV<-3>	−3	explicit form
IV<2>	+2	explicit form

The shift applies to the chord tones only — rootFreq is unchanged.

// Bass line: IV and V voiced an octave lower
const prog = chords(4, key, 'I IV< V< I')
yield cast(bass, prog, seq(4, '0,_,_,_'), ctx)