From my invaluable library : treatise on improvisation without partimentos, introducing gradually the functions. Written in Frankfurt 1889. This means: one year after Fernando Pessoa was born, and slavery was supposed to end… (but these informations I wrote here just to distract you, muhaha)
The result if this „functional“ method you find on many examples in music channel; not on „academic research„, also not on „youtubing“.
One of the best improvisers of our era (that I don’t tell who is, muhahah) also teached very similarly, but with more baroque examples; almost like De La Motte (who I agree using exclusively the detailed labelling of functions )