Better Jazz improvisation in TidalCycles

Agathe Herrou

TidalCycles

Haskell live-coding language
Pattern-based and cycle-based
Mini-notation
```
		
		  up "0*2 ~ [2 3] 5!2"
		
	      
```

Jazz

Jazz makes a freeer use of dissonance than classical music
Historically: chromatic approach
Formalised as altered chords and scales

Introductory example

Solo of Cannonball Adderley on All Blues

Often in Jazz, notes that are outside the scale can be played when improvising.
Here we have one section of the solo of Adderley on All Blues
As the name hints, this is a blues, and has a typical blues structure
The global scale is E mixolydian (E with 3 #), but it switches to A mixolydian on the A chords.
At the end of measure 4 we have a A# that is obviously not in the scale, that resolves on the B in the beginning of measure 5 (fifth of the chord)
On measure 7-8 we have a chromatic pattern that resolves on a G
and on measure 8 we have a repeated pattern with some chromaticism (D# is not in the scale)
And at the last measure the chromatic pattern transitions into the next section of the solo.
There is also a section that is played in the altered scale on the B7 and C7 chords

Jazz in TidalCycles

	      
		d1 $ stack [
		  up "<a'min7 d'min7 g'dom7 c'maj7>" # sound "superpiano" # legato 2,
		  up ((scale "<aeolian dorian mixolydian ionian>"
		  $ cat ["[0 1]*2",
		         struct "t*8" $ run 6])
		  |+ "<a d g c>")
		  # sound "superpiano"
		]

Chords and scales have to be associated manually
Constrained in the scale

To add chromaticism:

	      
		d1 $ stack [
		  up "<a'min7 d'min7 g'dom7 c'maj7>" # sound "superpiano" # legato 2,
		  up ((scale "<aeolian dorian mixolydian ionian>"
		  $ cat ["[0 1]*2",
		         struct "t*8" $ run 6])
		  |+ "<a d g c>"
		  |+ "0 1 0!6")
		  # sound "superpiano"
		]

Very tedious, impractical

Jazz in Strudel

Strudel: port of TidalCycles in JavaScript, running in the browser

Smooth voice leading
"Best" scales choice

Chromaticism

Idea: interpolate chromatically between anchor notes in a melody

Chromatise: Version 1

	      
		chromatise "[0 3] 5"
		tidal> "[[0 1 2] [3 4]] 5"

Problems:

Lookahead is not possible in the Tidal model
What about polyphony?

Already existing approximate solution:

	      
		smooth :: Fractional a => Pattern a -> Pattern a

Version 2

A less ambitious version: insert a fixed number of chromatic notes

	    
	      chromatise 2 "[0 3] 5"
	      tidal> "[[0 1 2] [3 4 5]] [5 6 7]"

Application: Chromatic approach

DEMO

scaleMod

Second idea: modify the scale on the fly

	      
		scaleMod :: Fractional a =>
		Pattern String -> ([a] -> [a]) -> Pattern Int -> Pattern a
		scaleMods :: Fractional a =>
		Pattern String -> ([[a] -> [a]]) -> Pattern Int -> Pattern a

	      
		scaleMod "major" (insert 6) $ run 8
		tidal> 0 2 4 5 6 7 9 11

	      
		scaleMods "major" [id, insert 6] $ run 8
		tidal> 0 2 4 5 7 9 11 12
		       0 2 4 5 6 7 9 11

Application: Bebop scales

Insert a note into a 7-degrees scale
$\Ra$ 8-degrees scale
Used for its rhythmic properties:
if played over 8 eighth-notes, it will end on the first scale note at next bar

Example from Giant Steps:

	      
		scaleMod "major" (insert 8) $ run 8

Application: Minor scales

Natural minor $\Ra$ harmonic minor:
raise the seventh degree by a semitone

Harmonic minor $\Ra$ melodic minor:
raise the sixth degree by a semitone

	      
		raiseDegree :: Fractional a => Int -> [a] -> [a]

	      
		scaleMods "minor" [id, raiseDegree 6] $ run 8
		> 0 2 3 5 7 8 10 12
		  0 2 3 5 7 8 11 12

	      
		scaleMods "minor" [id, raiseDegrees 5 6] $ run 8
		> 0 2 3 5 7 9 10 12
		  0 2 3 5 7 8 11 12

Conclusion

Added two functions chromatise and scaleMod to TidalCycles that make it easier to:

Insert chromatic passing notes
Modify scales on-the-fly

Future work:

Boolean masks in chromatise
Apply smooth to chromatic interpolation
More scale modification functions

Thanks for your attention!