Lessons · Advanced

Ornament spaces

Timed slots keep their length; substitutes scale to fit

% 'x?' is a TIMED slot: it derives x, or a rest of exactly x's
% length. The breath in bar 3 is that slot, and the asserts spell both
% readings — they differ only there. Bar 4 lands on beat 13 either
% way, and the strain runs sixteen beats either way:
 
bpm 30
key g harm
 
Fill   ::= 5/ 6/ 7/ '1/
Breath ::= Fill?
Air    ::= 5 _2 '1 7 '1 5 6 7 '1 _2 Breath 7 6 5 _2
 
assert Air#1 == 5 _2 '1 7 '1 5 6 7 '1 _2 - _2 7 6 5 _2
assert Air#2 == 5 _2 '1 7 '1 5 6 7 '1 _2 Fill 7 6 5 _2
 
Air#1 Air#2
 
 
% A SUBSTITUTE scales to fit: 'x?y' plays y in exactly x's span, and
% the asserts spell the mark that does it. The four-note turn takes
% bar 5's half note as four eighths, the three-note slide takes bar
% 6's as a triplet, and each slot is still two beats. The parens put
% the whole half note in the slot — bare, the '?' would hang on '_2':
 
Turn  ::= 7 6 5 6
Slide ::= 1 2 3
Close ::= (6 _2)?Turn 5 4 (3 _2)?Slide 2 1 2 _2 4 3 2 .7 1 _2
 
assert Close#2 == {Turn}/2 5 4 3 _2 2 1 2 _2 4 3 2 .7 1 _2
assert Close#3 == 6 _2 5 4 {Slide} _2 /3 2 1 2 _2 4 3 2 .7 1 _2
 
Close#4 Close#1
 
 
% The BASS is written once for all eight bars — half cadence under
% the strain, authentic under the close. Every reading of Air and
% Close is the same sixteen beats, so one bass fits all of them:
 
Bass ::= .1 _4 .1 _2 ..5 _2 .1 _2 ..5 _2 ..5 _4 ..6 _4 ..5 _4 ..4 _4 ..5 _2 .1 _2
 
{Air#1 Close#4, Bass}
 
 
% Every derivation is a performance: 'enum Close' prints all four
% readings of the second strain, each sixteen beats. The DOUBLE — the
% ornamented repeat — takes two of them over that same bass: pass one
% slides and keeps the breath, pass two turns, slides, and fills it:
 
enum Close
 
{Air#1 Close#3 Air#2 Close#1, Bass Bass}

% 'x?' is a TIMED slot: it derives x, or a rest of exactly x's
% length. The breath in bar 3 is that slot, and the asserts spell both
% readings — they differ only there. Bar 4 lands on beat 13 either
% way, and the strain runs sixteen beats either way:

bpm 30
key g harm

Fill   ::= 5/ 6/ 7/ '1/
Breath ::= Fill?
Air    ::= 5 _2 '1 7 '1 5 6 7 '1 _2 Breath 7 6 5 _2

assert Air#1 == 5 _2 '1 7 '1 5 6 7 '1 _2 - _2 7 6 5 _2
assert Air#2 == 5 _2 '1 7 '1 5 6 7 '1 _2 Fill 7 6 5 _2

Air#1 Air#2

% A SUBSTITUTE scales to fit: 'x?y' plays y in exactly x's span, and
% the asserts spell the mark that does it. The four-note turn takes
% bar 5's half note as four eighths, the three-note slide takes bar
% 6's as a triplet, and each slot is still two beats. The parens put
% the whole half note in the slot — bare, the '?' would hang on '_2':

Turn  ::= 7 6 5 6
Slide ::= 1 2 3
Close ::= (6 _2)?Turn 5 4 (3 _2)?Slide 2 1 2 _2 4 3 2 .7 1 _2

assert Close#2 == {Turn}/2 5 4 3 _2 2 1 2 _2 4 3 2 .7 1 _2
assert Close#3 == 6 _2 5 4 {Slide} _2 /3 2 1 2 _2 4 3 2 .7 1 _2

Close#4 Close#1

% The BASS is written once for all eight bars — half cadence under
% the strain, authentic under the close. Every reading of Air and
% Close is the same sixteen beats, so one bass fits all of them:

Bass ::= .1 _4 .1 _2 ..5 _2 .1 _2 ..5 _2 ..5 _4 ..6 _4 ..5 _4 ..4 _4 ..5 _2 .1 _2

{Air#1 Close#4, Bass}

% Every derivation is a performance: 'enum Close' prints all four
% readings of the second strain, each sixteen beats. The DOUBLE — the
% ornamented repeat — takes two of them over that same bass: pass one
% slides and keeps the breath, pass two turns, slides, and fills it:

enum Close

{Air#1 Close#3 Air#2 Close#1, Bass Bass}

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Ornament spaces · Pattern Engine