Home : Tune Toys : Expresso 
  Expresso takes a simple musical expression (literally "X") and mutates it. In each generation, transformations are applied to components of the expression. This is a fractal technique known as an L-system. The more generations there are, the larger and more complex the expression gets (and the longer it can take to compute). The output varies wildly, from boring to fascinating. Press "Mutate" a few times till you get something that looks interesting, then click on the image to play it. See Composer's Quarry for examples of output.

Transformations:
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After 20 generations the expression "X" became this:
step((((transpose(arpeggio(echo(step(shuffle(((((shuffle(transpose(X,-5) ) +echo(shuffle(shuffle(step(X,12) ) ) ,4,6) ) +transpose((step(step(step(step(X,12) ,12) ,12) ,12) +transpose(step(transpose(arpeggio(X) ,4) ,12) ,4) ) ,12) ) +transpose(arpeggio(shuffle((X+transpose(X,12) ) ) ) ,4) ) +transpose(((step(((X+transpose(echo(X,4,6) ,4) ) +transpose(X,7) ) ,12) +transpose((X|X) ,7) ) +transpose((arpeggio(transpose(X,-7) ) +transpose(X,7) ) ,12) ) ,7) ) ) ,12) ,4,6) ) ,-5) +transpose(echo(step(((step((((((transpose(X,-5) |X) +transpose((X+X) ,4) ) +transpose(arpeggio(shuffle((shuffle(X) +transpose((X+X) ,12) ) ) ) ,4) ) +transpose(transpose(shuffle(transpose(shuffle(((((X+transpose(X,4) ) +transpose(X,7) ) +transpose((X|X) ,7) ) +shuffle(transpose(X,-5) ) ) ) ,4) ) ,4) ,7) ) +((transpose(transpose(X,-7) ,4) |transpose(((X+X) |echo(X,4,6) ) ,-5) ) +transpose(transpose(transpose(transpose((X+X) ,-5) ,4) ,-5) ,-5) ) ) ,12) +transpose((((step((transpose(step(transpose(X,4) ,12) ,4) |transpose(transpose(transpose(X,-5) ,4) ,-7) ) ,12) +transpose((transpose(X,4) +transpose(transpose(shuffle(X) ,-5) ,12) ) ,4) ) |((((transpose(shuffle(step(X,12) ) ,4) +transpose(step(transpose(X,4) ,12) ,4) ) +transpose(transpose(shuffle((X+transpose(X,7) ) ) ,-7) ,7) ) |(arpeggio((X+X) ) |(arpeggio(X) +transpose((X+X) ,7) ) ) ) +transpose((((X|shuffle(X) ) +transpose(step((X+transpose(X,7) ) ,12) ,7) ) +transpose(((X+(((X+transpose(X,4) ) +transpose(X,7) ) +transpose(X,-5) ) ) |shuffle(step(step(X,12) ,12) ) ) ,12) ) ,7) ) ) +transpose(shuffle(step(transpose((shuffle(shuffle(step(((X+X) +transpose(step(X,12) ,7) ) ,12) ) ) +transpose(shuffle(arpeggio((((X+X) |(X+X) ) |X) ) ) ,12) ) ,-5) ,12) ) ,12) ) ,4) ) +transpose((echo(((transpose(echo(X,4,6) ,-7) +(step(echo(transpose(X,-5) ,4,6) ,12) +transpose((transpose(X,4) +transpose(transpose(X,-5) ,7) ) ,7) ) ) +transpose((transpose(X,-7) +shuffle(shuffle((step(X,12) +transpose(arpeggio((X|X) ) ,12) ) ) ) ) ,12) ) ,4,6) +transpose((((echo(shuffle(arpeggio(transpose(X,-7) ) ) ,4,6) +((shuffle(X) +transpose((step(shuffle(X) ,12) |step(transpose(X,-5) ,12) ) ,12) ) +transpose(arpeggio(transpose((X+transpose(X,12) ) ,4) ) ,7) ) ) +transpose(transpose(transpose(arpeggio(step(X,12) ) ,4) ,4) ,4) ) +transpose(echo(transpose(step(shuffle(shuffle(step((X+transpose(transpose(X,-5) ,12) ) ,12) ) ) ,12) ,-5) ,4,6) ,7) ) ,4) ) ,7) ) ,12) ,4,6) ,4) ) +transpose(transpose(transpose(transpose(arpeggio((shuffle((X+transpose(shuffle(X) ,12) ) ) +transpose((echo(transpose((X+transpose(X,7) ) ,4) ,4,6) +transpose(((transpose(transpose(X,-5) ,-5) |transpose(transpose((X|X) ,-5) ,-5) ) +(shuffle(X) +transpose((X|X) ,-5) ) ) ,7) ) ,12) ) ) ,-5) ,-7) ,-5) ,7) ) +transpose(((echo(shuffle(transpose((transpose(X,-5) +arpeggio(arpeggio(X) ) ) ,-7) ) ,4,6) +transpose(arpeggio(transpose(shuffle(transpose(transpose(transpose(transpose(arpeggio(transpose(transpose(X,4) ,4) ) ,-5) ,-7) ,-7) ,4) ) ,-5) ) ,12) ) +transpose(arpeggio(((((shuffle(transpose(transpose((transpose(((arpeggio(transpose(X,4) ) +transpose(((X+X) +transpose(((X+transpose(X,12) ) +transpose(X,12) ) ,12) ) ,4) ) +transpose(((X+transpose(X,12) ) +transpose((X|X) ,7) ) ,7) ) ,-7) +transpose(shuffle(shuffle(shuffle(X) ) ) ,12) ) ,4) ,4) ) +transpose((step(shuffle(transpose(X,-5) ) ,12) +transpose(((shuffle((transpose(X,-5) +X) ) +transpose(((step(X,12) |X) +transpose(transpose(shuffle(X) ,-7) ,12) ) ,7) ) +(arpeggio(X) |(step(X,12) +(X+transpose(X,12) ) ) ) ) ,7) ) ,-7) ) +((transpose((((X+transpose(X,4) ) +transpose(X,7) ) +((X+transpose(X,7) ) +echo(X,4,6) ) ) ,-5) +transpose(arpeggio((((((transpose(X,4) +transpose(transpose(X,-5) ,4) ) +transpose((step(X,12) +transpose(X,12) ) ,7) ) +step(((X+transpose((X|X) ,4) ) +transpose(X,7) ) ,12) ) +transpose(transpose(step(arpeggio(((transpose(X,4) +transpose(X,4) ) +transpose(arpeggio(X) ,7) ) ) ,12) ,-7) ,12) ) +transpose((transpose(step(transpose(((step(transpose(X,4) ,12) +transpose(echo(X,4,6) ,4) ) +transpose((X+transpose(arpeggio(X) ,7) ) ,7) ) ,-5) ,12) ,-5) +transpose(transpose(shuffle(step((X+X) ,12) ) ,-5) ,7) ) ,7) ) ) ,7) ) |arpeggio(shuffle(arpeggio(step(arpeggio(transpose(step(arpeggio(X) ,12) ,4) ) ,12) ) ) ) ) ) |((echo(transpose(transpose(transpose((X+(X+X) ) ,4) ,4) ,-5) ,4,6) +((arpeggio(shuffle((X+transpose(X,7) ) ) ) |step((arpeggio(X) +(X|X) ) ,12) ) |(step(((X+X) +transpose(step(X,12) ,4) ) ,12) +transpose(transpose(step(echo(transpose(echo(X,4,6) ,4) ,4,6) ,12) ,-5) ,7) ) ) ) +transpose((transpose(arpeggio(arpeggio(transpose(X,-7) ) ) ,-7) +(step(arpeggio(X) ,12) +shuffle(arpeggio(X) ) ) ) ,4) ) ) +transpose(arpeggio(transpose((arpeggio(step((((X+transpose(shuffle(X) ,12) ) +transpose((transpose(step(X,12) ,-7) +(X+X) ) ,12) ) +transpose(shuffle(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,-5) ) ,7) ) ,12) ) +transpose(shuffle(step(transpose(transpose(X,4) ,4) ,12) ) ,12) ) ,-7) ) ,7) ) ) ,7) ) ,7) ) ,12)
random seed used was 164175387 EXPR = transpose(((transpose(((transpose(shuffle(arpeggio((((((step(X,12) +transpose(echo(X,4,6) ,12) ) +transpose(step((arpeggio((X+transpose(X,7) ) ) |(X+transpose(X,7) ) ) ,12) ,4) ) +transpose(shuffle((((X+transpose(X,7) ) +transpose((X|X) ,4) ) +transpose(transpose(X,-5) ,7) ) ) ,7) ) +transpose((transpose(shuffle(X) ,4) +(transpose(transpose(X,-7) ,4) |step(X,12) ) ) ,4) ) +transpose((transpose(((X+transpose(X,-7) ) +step(echo(X,4,6) ,12) ) ,-7) +transpose((transpose(X,-5) +transpose(echo(step(X,12) ,4,6) ,-7) ) ,12) ) ,7) ) ) ) ,-7) +((step((transpose(echo((((((X+transpose(X,4) ) +transpose(X,7) ) +step(X,12) ) +transpose(echo((X+transpose(X,12) ) ,4,6) ,4) ) +transpose((X|X) ,7) ) ,4,6) ,-7) +(echo(step(shuffle(step(X,12) ) ,12) ,4,6) +transpose(transpose(arpeggio((((X|X) +transpose(X,4) ) +transpose(echo(X,4,6) ,7) ) ) ,-5) ,12) ) ) ,12) +transpose(((arpeggio((transpose(arpeggio(X) ,4) +transpose(transpose(step(step(X,12) ,12) ,-5) ,7) ) ) +transpose((shuffle(((X+transpose(((((X+X) +transpose(transpose(X,-5) ,4) ) +transpose(X,7) ) +(step(X,12) +transpose(X,-5) ) ) ,4) ) +transpose(step((X+((X+X) +(X+transpose(X,7) ) ) ) ,12) ,7) ) ) +transpose(shuffle((transpose((((X+transpose(X,12) ) +transpose(X,4) ) +transpose(transpose(X,-7) ,7) ) ,-7) |(echo(X,4,6) +transpose(transpose((X+X) ,-7) ,-7) ) ) ) ,7) ) ,12) ) +(((transpose(shuffle(shuffle(shuffle(shuffle(transpose(X,4) ) ) ) ) ,-5) +transpose(step(transpose(((transpose(step(X,12) ,-7) |step(X,12) ) +step((X+transpose(X,12) ) ,12) ) ,-5) ,12) ,12) ) +transpose(step((shuffle(arpeggio((transpose(arpeggio(X) ,4) +transpose(((X+X) +transpose((X+transpose(X,12) ) ,12) ) ,12) ) ) ) |((transpose(transpose((X+X) ,4) ,-5) +arpeggio((X|shuffle(X) ) ) ) |shuffle((step(X,12) +transpose(X,-5) ) ) ) ) ,12) ,7) ) +((arpeggio(transpose(transpose((X|X) ,-5) ,-5) ) +(((X+transpose(X,7) ) |((X+X) +transpose((X+X) ,7) ) ) +step(arpeggio(X) ,12) ) ) +transpose((arpeggio((((X+transpose(X,12) ) +transpose(arpeggio(X) ,4) ) +transpose((X|(X+transpose(X,7) ) ) ,7) ) ) +((X+X) +transpose(arpeggio((X+transpose(X,12) ) ) ,12) ) ) ,7) ) ) ) ,4) ) +transpose(transpose(echo(arpeggio(transpose(echo((X+transpose(X,7) ) ,4,6) ,4) ) ,4,6) ,-5) ,7) ) ) +((echo(transpose(arpeggio(transpose(arpeggio(((arpeggio(step(X,12) ) +arpeggio(step(X,12) ) ) |step((X|arpeggio(shuffle(X) ) ) ,12) ) ) ,4) ) ,4) ,4,6) +transpose(transpose(((arpeggio(transpose((transpose(((X+transpose(X,12) ) +transpose(transpose(X,-5) ,12) ) ,-7) |transpose(arpeggio(transpose(X,-5) ) ,4) ) ,4) ) +transpose(transpose(arpeggio((shuffle(step(shuffle(transpose((X+transpose(X,12) ) ,-5) ) ,12) ) |((transpose(step(transpose(transpose(step(X,12) ,-5) ,4) ,12) ,4) +transpose(transpose(transpose(((X+X) +X) ,-7) ,-5) ,4) ) +transpose(((((X+transpose(X,12) ) +X) |shuffle(((X+transpose(X,4) ) +transpose((X+transpose(X,12) ) ,7) ) ) ) +step(echo(shuffle(arpeggio(X) ) ,4,6) ,12) ) ,7) ) ) ) ,-5) ,4) ) +transpose(transpose((shuffle((arpeggio(X) +step(step((transpose(X,-5) +transpose(step(shuffle(X) ,12) ,12) ) ,12) ,12) ) ) |transpose((X+(X|X) ) ,4) ) ,4) ,7) ) ,-7) ,4) ) +transpose(transpose(step(step(((arpeggio(arpeggio((X|((X+transpose(X,4) ) +transpose(X,7) ) ) ) ) +transpose(((step(arpeggio(X) ,12) +transpose(((X+X) +transpose(transpose(X,-7) ,12) ) ,-7) ) +transpose((arpeggio(X) +((X+transpose(X,7) ) +step(X,12) ) ) ,4) ) ,4) ) +transpose(((step((X+transpose(X,7) ) ,12) |(((X+transpose(X,4) ) +transpose(X,7) ) +transpose(X,4) ) ) |transpose((step(shuffle(X) ,12) +transpose(transpose(step(X,12) ,-5) ,12) ) ,-7) ) ,7) ) ,12) ,12) ,-7) ,7) ) ) ,-5) +transpose(shuffle(transpose((shuffle(step(echo(((((step(X,12) +transpose((shuffle(X) +(X|X) ) ,4) ) +transpose((((X+transpose(X,4) ) +transpose(X,7) ) |transpose(X,-5) ) ,7) ) |transpose(step((X|X) ,12) ,-5) ) |(arpeggio(X) +transpose(arpeggio(shuffle(shuffle(((X+transpose(X,4) ) +transpose(X,7) ) ) ) ) ,7) ) ) ,4,6) ,12) ) +arpeggio((((shuffle(shuffle(transpose(X,4) ) ) +transpose(step(((transpose(((arpeggio(X) +transpose(X,4) ) +transpose(X,7) ) ,-5) +transpose(arpeggio((X+transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ) ) ,4) ) +transpose((((X+X) |X) +transpose(arpeggio(X) ,7) ) ,7) ) ,12) ,12) ) |transpose(transpose(transpose((X+transpose(X,7) ) ,4) ,-7) ,-5) ) +transpose((arpeggio(shuffle(arpeggio((echo(X,4,6) |(X+transpose(X,7) ) ) ) ) ) +(shuffle(transpose((transpose(X,-7) +transpose(echo(X,4,6) ,7) ) ,4) ) +arpeggio((step(X,12) +transpose((X|transpose(X,-5) ) ,7) ) ) ) ) ,12) ) ) ) ,-7) ) ,4) ) +transpose(transpose(((((((step(((shuffle(echo((transpose(shuffle((X+transpose(X,12) ) ) ,-7) +transpose(transpose(transpose((X+X) ,-5) ,-5) ,12) ) ,4,6) ) +transpose((step((X+transpose(X,7) ) ,12) |step(shuffle(arpeggio(X) ) ,12) ) ,7) ) +arpeggio((shuffle(transpose(arpeggio(shuffle((X|X) ) ) ,-5) ) |(transpose(transpose(((step(X,12) +transpose(arpeggio(X) ,4) ) +transpose(shuffle(X) ,7) ) ,4) ,4) +transpose(transpose((X+(X+X) ) ,-5) ,7) ) ) ) ) ,12) +transpose(echo(transpose(echo(((transpose(transpose(X,-5) ,-7) +transpose(arpeggio(shuffle(X) ) ,4) ) +transpose((echo(X,4,6) +transpose(step((X|X) ,12) ,12) ) ,7) ) ,4,6) ,-5) ,4,6) ,4) ) +transpose(echo(transpose(arpeggio(((step(((X+transpose(X,4) ) +transpose(X,7) ) ,12) +transpose(echo(arpeggio(X) ,4,6) ,12) ) +step(arpeggio(step(X,12) ) ,12) ) ) ,4) ,4,6) ,7) ) +transpose(echo((((echo(shuffle((X+transpose(shuffle(X) ,7) ) ) ,4,6) +transpose(arpeggio(arpeggio(arpeggio(step(X,12) ) ) ) ,12) ) +(shuffle(((transpose(X,4) +transpose(X,4) ) +transpose(X,7) ) ) |(step((X|(X+X) ) ,12) +transpose(step(((echo(X,4,6) +transpose(step(arpeggio(X) ,12) ,4) ) +transpose(((X+X) |step(X,12) ) ,7) ) ,12) ,12) ) ) ) +transpose((transpose(shuffle(transpose((step(transpose(step(X,12) ,-7) ,12) +(transpose(echo(X,4,6) ,-5) |step(X,12) ) ) ,4) ) ,-5) +transpose((transpose((arpeggio(X) +transpose((X|shuffle(X) ) ,12) ) ,4) |transpose(arpeggio(transpose(transpose(X,-5) ,4) ) ,-5) ) ,-7) ) ,7) ) ,4,6) ,4) ) +transpose(transpose(transpose(((echo(transpose(echo((transpose(transpose(arpeggio((X|X) ) ,-5) ,-7) +transpose(step(step(arpeggio((((X+transpose(X,4) ) +transpose(X,7) ) +step(X,12) ) ) ,12) ,12) ,12) ) ,4,6) ,4) ,4,6) +transpose(((arpeggio(transpose(transpose(X,-5) ,-5) ) |(echo(transpose(((transpose(arpeggio(X) ,4) |shuffle(X) ) |transpose(transpose(X,-7) ,-5) ) ,4) ,4,6) +transpose(step(transpose(arpeggio(X) ,4) ,12) ,12) ) ) +transpose((step((arpeggio(shuffle((step(step(X,12) ,12) +transpose(transpose(step((X+transpose(X,12) ) ,12) ,4) ,12) ) ) ) +transpose(shuffle((step(X,12) +transpose((X+transpose(X,-7) ) ,12) ) ) ,7) ) ,12) +transpose((arpeggio(step(echo(arpeggio(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,-5) ) ,4,6) ,12) ) +transpose((transpose(step(shuffle(X) ,12) ,4) |(step(shuffle(arpeggio(echo(X,4,6) ) ) ,12) +transpose(arpeggio((transpose(X,-7) +step(X,12) ) ) ,7) ) ) ,7) ) ,7) ) ,7) ) ,7) ) +transpose(transpose(transpose(transpose(step(((X+X) |shuffle(X) ) ,12) ,-7) ,4) ,-7) ,12) ) ,-5) ,-7) ,7) ) +arpeggio(step(step(step((step((transpose((echo(arpeggio(X) ,4,6) +(arpeggio(X) |X) ) ,4) |step(step(((transpose(X,-5) +transpose(step(X,12) ,12) ) +step(echo(X,4,6) ,12) ) ,12) ,12) ) ,12) +transpose((transpose(echo((step(X,12) +step(X,12) ) ,4,6) ,-7) +transpose(echo(arpeggio((transpose(X,-5) |X) ) ,4,6) ,7) ) ,7) ) ,12) ,12) ,12) ) ) +transpose(echo(((((transpose((shuffle(step(step(shuffle(arpeggio(X) ) ,12) ,12) ) +transpose(arpeggio((step(X,12) +transpose(shuffle(X) ,12) ) ) ,7) ) ,4) |transpose(shuffle(step(shuffle(transpose(shuffle((X+transpose(transpose(X,4) ,12) ) ) ,-5) ) ,12) ) ,-5) ) +transpose(shuffle(transpose(step(shuffle(step(transpose(transpose((step(X,12) +transpose(((X|X) +X) ,12) ) ,-7) ,4) ,12) ) ,12) ,4) ) ,7) ) +transpose(((((arpeggio(step(arpeggio(shuffle(step(X,12) ) ) ,12) ) |(transpose(((step(transpose(X,-5) ,12) +transpose(transpose(transpose(X,4) ,-5) ,4) ) +transpose(echo(echo(step(X,12) ,4,6) ,4,6) ,7) ) ,4) +transpose(echo(arpeggio(((shuffle(X) +transpose(X,-5) ) +transpose(((X+transpose(X,12) ) +transpose(transpose(X,-5) ,7) ) ,7) ) ) ,4,6) ,12) ) ) +transpose(step(((transpose(step(X,12) ,-7) +transpose(transpose(arpeggio(transpose(step(step(X,12) ,12) ,4) ) ,4) ,4) ) +transpose(transpose((X|X) ,-5) ,7) ) ,12) ,7) ) +transpose(step((step(X,12) +transpose((shuffle(shuffle(X) ) |(arpeggio(arpeggio(X) ) +transpose(step(X,12) ,7) ) ) ,7) ) ,12) ,-5) ) |shuffle(step((transpose(step(shuffle((((X|X) +transpose((X|X) ,7) ) +transpose(echo(arpeggio(X) ,4,6) ,7) ) ) ,12) ,-5) |(transpose((((step(step(X,12) ,12) +transpose(transpose(step(X,12) ,4) ,4) ) +transpose(shuffle(transpose(X,4) ) ,7) ) +((arpeggio(arpeggio(X) ) +(X+transpose(X,12) ) ) +step((((transpose(X,4) +transpose((X|X) ,4) ) +transpose(X,7) ) |transpose(shuffle(X) ,4) ) ,12) ) ) ,4) |shuffle((arpeggio(transpose(X,-7) ) +arpeggio(shuffle(transpose(X,-7) ) ) ) ) ) ) ,12) ) ) ,4) ) +transpose(arpeggio((step(((transpose((((((((X+transpose(X,7) ) |transpose((X|X) ,-7) ) +transpose((X|X) ,4) ) +transpose((arpeggio(step(X,12) ) +(X|((X+transpose(X,4) ) +transpose(X,7) ) ) ) ,7) ) +transpose(step(X,12) ,4) ) +transpose(transpose(transpose(shuffle(arpeggio(X) ) ,-5) ,-5) ,7) ) |((transpose(((transpose(X,-7) +shuffle(X) ) +transpose(X,12) ) ,-5) +transpose((X+transpose(transpose(X,-5) ,12) ) ,7) ) +transpose(shuffle(echo((shuffle(X) +transpose(X,7) ) ,4,6) ) ,7) ) ) ,4) +transpose((shuffle(shuffle(((X+transpose(step(X,12) ,4) ) +transpose(transpose(X,-5) ,7) ) ) ) +transpose(((arpeggio(step(step(transpose(arpeggio(X) ,-5) ,12) ,12) ) +transpose(transpose(X,-5) ,4) ) +step((((echo(shuffle((X+transpose(X,12) ) ) ,4,6) +((X+transpose(transpose(step(X,12) ,4) ,4) ) +transpose(transpose(X,-5) ,7) ) ) +transpose(transpose(((shuffle(X) +transpose(step(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ,4) ) +transpose((arpeggio(X) +transpose(X,7) ) ,7) ) ,-7) ,4) ) +transpose(transpose(((shuffle(X) +shuffle(X) ) +(arpeggio(((X+transpose(X,4) ) +transpose(X,7) ) ) +transpose(shuffle(X) ,7) ) ) ,4) ,7) ) ,12) ) ,12) ) ,4) ) +transpose(arpeggio((arpeggio(transpose(((X+transpose(X,12) ) |shuffle(shuffle(X) ) ) ,4) ) +transpose(arpeggio(arpeggio(arpeggio((X+transpose(X,12) ) ) ) ) ,12) ) ) ,7) ) ,12) +transpose((((transpose(transpose(((X|X) +transpose(X,12) ) ,-7) ,-7) |arpeggio(shuffle(transpose(step((((X+transpose(shuffle(X) ,4) ) +transpose(echo(X,4,6) ,7) ) |transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ) ,12) ,4) ) ) ) +transpose(transpose(((arpeggio(arpeggio(step(X,12) ) ) |(transpose(transpose(X,-7) ,-5) +transpose(step((echo(X,4,6) +transpose(X,4) ) ,12) ,-7) ) ) +transpose(transpose((shuffle(X) |transpose(X,-7) ) ,-5) ,7) ) ,-7) ,4) ) +transpose((((arpeggio(shuffle((X+X) ) ) +transpose((transpose(transpose(X,-5) ,4) +transpose(transpose(shuffle(X) ,-7) ,12) ) ,4) ) +transpose(step((X+transpose(X,12) ) ,12) ,7) ) +transpose(((arpeggio(arpeggio(X) ) |transpose(X,4) ) |transpose((arpeggio(X) +transpose(X,7) ) ,-7) ) ,-7) ) ,7) ) ,12) ) ) ,7) ) ,4,6) ,12) ) ,4) ,7) ) ,-5)
random seed used was 0

The algorithm for Expresso is written in KeyKit, and here's the source code.