Scales, Chords & Intervals

The names Scale(), Key(), chord(), interval() and chord literals accept. The functions and the Scale and Key types are in the std/theory reference.

Scales

Accepted by Scale(name), Key(root, name) and track.set_key(name, root). scale_names() returns the names, without the aliases.

Scale	Aliases	Notes	Intervals (semitones)	Character
`"major"`	`"ionian"`	7	0 2 4 5 7 9 11	Bright, happy, resolved
`"minor"`	`"aeolian"`	7	0 2 3 5 7 8 10	Dark, melancholic
`"dorian"`	—	7	0 2 3 5 7 9 10	Minor with a bright 6th
`"phrygian"`	—	7	0 1 3 5 7 8 10	Spanish, exotic
`"lydian"`	—	7	0 2 4 6 7 9 11	Dreamy, floating
`"mixolydian"`	—	7	0 2 4 5 7 9 10	Bluesy major, rock
`"locrian"`	—	7	0 1 3 5 6 8 10	Unstable, diminished
`"harmonic_minor"`	—	7	0 2 3 5 7 8 11	Classical tension
`"melodic_minor"`	—	7	0 2 3 5 7 9 11	Jazz minor
`"pentatonic_major"`	—	5	0 2 4 7 9	Open, folk
`"pentatonic_minor"`	—	5	0 3 5 7 10	Blues, rock riffs
`"blues"`	—	6	0 3 5 6 7 10	Gritty, soulful
`"whole_tone"`	—	6	0 2 4 6 8 10	Dreamlike, ambiguous
`"chromatic"`	—	12	0 1 2 3 4 5 6 7 8 9 10 11	All semitones

assert scale_names().length() == 14;
assert Scale("pentatonic_minor").length() == 5;
print(Scale("ionian").intervals());   // [0, 2, 4, 5, 7, 9, 11] — the major scale

A custom scale is an interval array starting at 0 and strictly ascending; fractional values are microtonal. Scale(intervals, period) sets a repeat period other than 12 semitones. load_scala(name) reads a Scala .scl file.

Chord qualities

Accepted by chord(root, quality), key.chord(degree, quality), and chord literals (C4:min7, ^2:min7). chord_names() returns the names.

A chord literal writes each quality by its short name (maj, min, 5 for major, minor, power). Literals also accept five shorthands that chord() and key.chord() do not: m (min), m7 (min7), m9 (min9), m6 (min6) and dom (dom7).

Quality	Aliases	Notes	Intervals (semitones)	Character
`"major"`	`"maj"`	3	0 4 7	Bright, stable
`"minor"`	`"min"`	3	0 3 7	Dark, melancholic
`"dim"`	—	3	0 3 6	Tense, unstable
`"aug"`	—	3	0 4 8	Bright, unsettled
`"7"`	`"dom7"`	4	0 4 7 10	Bluesy, wants to resolve
`"maj7"`	—	4	0 4 7 11	Lush, jazzy
`"min7"`	—	4	0 3 7 10	Smooth, mellow
`"dim7"`	—	4	0 3 6 9	Dramatic, symmetrical
`"aug7"`	—	4	0 4 8 10	Altered dominant
`"sus2"`	—	3	0 2 7	Open, ambiguous
`"sus4"`	—	3	0 5 7	Suspended, tense
`"6"`	`"maj6"`	4	0 4 7 9	Warm, vintage
`"min6"`	—	4	0 3 7 9	Bittersweet
`"9"`	—	5	0 4 7 10 14	Rich dominant
`"maj9"`	—	5	0 4 7 11 14	Lush, expansive
`"min9"`	—	5	0 3 7 10 14	Smooth, complex
`"add9"`	—	4	0 4 7 14	Bright, open
`"power"`	`"5"`	2	0 7	Neutral, heavy

assert chord_names().length() == 18;
print(chord(C4, "min7"));    // [C4, Eb4, G4, Bb4]
print(chord(C4, "power"));   // [C4, G4]

An inversion (chord(root, quality, n), or ~n in a literal) moves the lowest n notes up an octave; a negative n moves the highest notes down.

Intervals

Accepted by interval(note, name). Case matters: "M3" is a major third, "m3" a minor third.

Name	Aliases	Interval	Semitones
`"m2"`	—	Minor 2nd	1
`"M2"`	—	Major 2nd	2
`"m3"`	—	Minor 3rd	3
`"M3"`	—	Major 3rd	4
`"P4"`	—	Perfect 4th	5
`"tritone"`	`"TT"`	Tritone	6
`"P5"`	—	Perfect 5th	7
`"m6"`	—	Minor 6th	8
`"M6"`	—	Major 6th	9
`"m7"`	—	Minor 7th	10
`"M7"`	—	Major 7th	11
`"P8"`	`"oct"`	Octave	12

assert interval(C4, "P5") == G4;
assert interval(C4, "TT") == interval(C4, "tritone");
print(interval(C4, "m3"));   // Eb4