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 19 generations the expression "X" became this:
((step(arpeggio((step(transpose(step((echo(arpeggio(transpose(X,4) ) ,4,6) +transpose(transpose(step(((X+transpose(X,12) ) +transpose((X+transpose(X,7) ) ,12) ) ,12) ,-5) ,12) ) ,12) ,-7) ,12) +step((echo((((step(echo(((X+transpose(X,4) ) +transpose(X,7) ) ,4,6) ,12) +transpose(transpose(((((arpeggio(X) +transpose(transpose(X,4) ,4) ) +transpose(X,7) ) +transpose((arpeggio(X) +X) ,12) ) |(arpeggio(step(X,12) ) +transpose(((echo(X,4,6) +transpose(X,4) ) +transpose(transpose(X,-7) ,7) ) ,12) ) ) ,-7) ,7) ) +transpose((transpose(X,-7) +transpose(X,7) ) ,12) ) +transpose((((X|(X+X) ) +transpose(transpose(transpose(X,-7) ,4) ,4) ) +transpose(transpose(X,4) ,7) ) ,-5) ) ,4,6) |transpose(arpeggio(((echo(shuffle(echo((X|X) ,4,6) ) ,4,6) +transpose((step(step((X|((X+transpose(X,4) ) +transpose(X,7) ) ) ,12) ,12) +(((arpeggio(X) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,7) ) +transpose(X,4) ) +transpose(shuffle((X+transpose((X+transpose(X,12) ) ,12) ) ) ,7) ) ) ,4) ) +transpose(transpose(echo(transpose(arpeggio(shuffle(X) ) ,-5) ,4,6) ,-7) ,7) ) ) ,-7) ) ,12) ) ) ,12) +(arpeggio((transpose((((echo((X|X) ,4,6) +transpose(echo(arpeggio(X) ,4,6) ,7) ) +transpose((((((((X+transpose(X,4) ) +transpose(X,7) ) |transpose(X,4) ) +transpose(transpose(X,-7) ,4) ) +transpose(step(echo(X,4,6) ,12) ,7) ) +transpose((shuffle(X) |X) ,4) ) +transpose((echo(X,4,6) +transpose(arpeggio((X+transpose(X,-5) ) ) ,12) ) ,7) ) ,7) ) +transpose(((((((shuffle(((X+X) +transpose(((step(X,12) +transpose(transpose(X,4) ,4) ) +transpose(step(X,12) ,7) ) ,7) ) ) +transpose(((transpose(transpose(X,-5) ,4) +transpose(transpose(shuffle(step(X,12) ) ,-5) ,7) ) +transpose(step(((transpose(X,4) +transpose(step(X,12) ,4) ) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,7) ) ,12) ,12) ) ,4) ) +transpose((echo(transpose(X,-7) ,4,6) +transpose(((X+transpose(X,12) ) +((transpose(X,-7) +transpose(shuffle(X) ,4) ) +transpose(transpose(X,-5) ,7) ) ) ,12) ) ,7) ) +transpose((((echo(((X+transpose(X,4) ) +transpose(X,7) ) ,4,6) +transpose(shuffle(X) ,12) ) +arpeggio(transpose(X,4) ) ) +transpose(transpose((((X+transpose(X,4) ) +transpose(X,7) ) +((X+transpose(X,12) ) +transpose((X+X) ,7) ) ) ,-5) ,7) ) ,4) ) +transpose((((((X+transpose(X,4) ) +transpose(X,7) ) +transpose((X|(X+transpose(X,12) ) ) ,7) ) |transpose(transpose(X,4) ,-7) ) +((step(X,12) |(X+transpose(transpose(X,4) ,7) ) ) +transpose((transpose(X,4) +X) ,12) ) ) ,7) ) +transpose((arpeggio(transpose(echo((shuffle((((X+transpose(X,4) ) +transpose(X,7) ) +transpose((X+transpose(X,-5) ) ,7) ) ) +transpose(step(((X+arpeggio(X) ) +transpose((shuffle(X) +transpose(X,12) ) ,7) ) ,12) ,12) ) ,4,6) ,-7) ) +transpose((echo(((arpeggio(X) +transpose((X|((X+transpose(X,4) ) +transpose(X,7) ) ) ,4) ) +transpose(((X+transpose(X,12) ) +transpose(echo(X,4,6) ,7) ) ,7) ) ,4,6) |transpose((step(shuffle(X) ,12) +transpose(echo(arpeggio(X) ,4,6) ,7) ) ,4) ) ,7) ) ,4) ) +transpose(echo((((transpose((transpose(X,4) +transpose((X+transpose((X+transpose(X,12) ) ,12) ) ,7) ) ,-5) +transpose(transpose(echo(X,4,6) ,4) ,4) ) +transpose(step(transpose(transpose(step((X|X) ,12) ,-7) ,-7) ,12) ,7) ) +transpose((echo(X,4,6) +transpose(arpeggio(step(X,12) ) ,7) ) ,12) ) ,4,6) ,7) ) ,12) ) ,4) +transpose(transpose(((echo(transpose((shuffle(arpeggio((((X+transpose(X,12) ) |((X+transpose(X,4) ) +transpose(X,7) ) ) +transpose(((shuffle(X) +transpose(shuffle((X|X) ) ,4) ) +transpose((transpose(X,-5) +transpose(X,12) ) ,7) ) ,7) ) ) ) +transpose(((X|((arpeggio(X) +transpose((arpeggio(X) +(X+transpose(X,7) ) ) ,4) ) +transpose(((X+transpose(echo(X,4,6) ,4) ) +transpose(shuffle(X) ,7) ) ,7) ) ) |((X+transpose(X,12) ) +transpose(transpose(step(transpose(transpose(echo(X,4,6) ,4) ,4) ,12) ,-7) ,7) ) ) ,12) ) ,-5) ,4,6) +transpose((echo((echo(X,4,6) +transpose(echo((X+transpose(X,12) ) ,4,6) ,7) ) ,4,6) +transpose(transpose(echo(transpose(X,-7) ,4,6) ,-7) ,7) ) ,4) ) +transpose(step(shuffle(step(echo(transpose(((((X+transpose(X,12) ) +transpose((arpeggio(X) |X) ,4) ) +transpose(transpose(step(X,12) ,-5) ,7) ) +transpose((X+transpose((X|X) ,7) ) ,12) ) ,-5) ,4,6) ,12) ) ,12) ,7) ) ,-7) ,12) ) ) +transpose(echo(((transpose((((((((arpeggio(transpose(X,-7) ) +transpose(shuffle(((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(X,4) ) +transpose(X,7) ) ) ,4) ) +transpose(((echo(X,4,6) +(X+transpose(X,7) ) ) +transpose(((transpose(transpose(X,4) ,4) +transpose(arpeggio(X) ,4) ) +transpose(arpeggio(transpose(X,-7) ) ,7) ) ,12) ) ,7) ) +transpose((transpose((X+X) ,-7) +transpose(arpeggio(arpeggio(step(X,12) ) ) ,12) ) ,7) ) +transpose((transpose((((X+transpose(X,7) ) |echo(X,4,6) ) +transpose(transpose(X,-7) ,12) ) ,-5) |step(step((((X+X) +transpose((echo(X,4,6) |X) ,4) ) +transpose((transpose(X,-7) +transpose((X+transpose(X,12) ) ,12) ) ,7) ) ,12) ,12) ) ,12) ) +transpose(arpeggio(arpeggio(((transpose(X,-7) +transpose((X|((X+transpose(X,4) ) +transpose(X,7) ) ) ,4) ) +transpose(transpose(transpose(X,-5) ,-7) ,7) ) ) ) ,12) ) +transpose(((transpose(((((((X+transpose(X,12) ) +transpose(X,4) ) +transpose(transpose(X,-7) ,7) ) |((transpose(X,4) +transpose(X,4) ) +transpose(X,7) ) ) +transpose((X|X) ,4) ) +transpose(X,7) ) ,-5) +transpose((arpeggio(echo(transpose(transpose(X,4) ,-5) ,4,6) ) +transpose((transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) +transpose(shuffle(X) ,7) ) ,7) ) ,4) ) +transpose((transpose((((X|X) |X) +(X|transpose(X,4) ) ) ,-7) +transpose((step(transpose(X,-5) ,12) +transpose(((shuffle(X) +X) +transpose((arpeggio(X) +transpose(echo(X,4,6) ,12) ) ,7) ) ,7) ) ,7) ) ,7) ) ,4) ) +transpose((step(((((X+X) +transpose(X,12) ) +transpose(echo(((X+transpose(transpose(X,4) ,4) ) +transpose(X,7) ) ,4,6) ,4) ) +transpose((echo(arpeggio((X+X) ) ,4,6) +transpose(step(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ,7) ) ,7) ) ,12) +transpose(((X|X) +transpose((transpose(X,-5) +transpose((X|(X+transpose(X,7) ) ) ,12) ) ,12) ) ,7) ) ,7) ) ,-5) +transpose(transpose(echo((((echo(echo(echo((X+X) ,4,6) ,4,6) ,4,6) |echo(shuffle((X|X) ) ,4,6) ) +transpose(step(echo(step(X,12) ,4,6) ,12) ,7) ) +transpose(shuffle(transpose(X,-5) ) ,12) ) ,4,6) ,-7) ,12) ) |(transpose(shuffle(transpose(transpose(transpose((X+transpose(X,12) ) ,-7) ,-7) ,4) ) ,4) +transpose(((step(echo(echo(transpose(X,-7) ,4,6) ,4,6) ,12) +transpose(arpeggio((X+transpose(X,7) ) ) ,12) ) |(shuffle((step((transpose(((X|X) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ) ,-5) +transpose(shuffle(echo(X,4,6) ) ,-7) ) ,12) +transpose(((echo(arpeggio(step(X,12) ) ,4,6) +transpose((shuffle((X+X) ) +(transpose(X,4) +transpose((echo(X,4,6) +transpose(X,7) ) ,12) ) ) ,4) ) +transpose(arpeggio(transpose(shuffle(X) ,-7) ) ,7) ) ,12) ) ) +arpeggio(((transpose(((transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,-7) +transpose(((X+transpose(X,4) ) +transpose((X|X) ,7) ) ,4) ) +transpose((X+transpose((X+X) ,12) ) ,7) ) ,-5) |step(shuffle(((X+transpose(X,7) ) +transpose((X+transpose(X,12) ) ,12) ) ) ,12) ) +transpose((shuffle(((transpose(X,4) |X) +transpose(step(X,12) ,12) ) ) |((X+transpose(X,7) ) |transpose(X,-5) ) ) ,12) ) ) ) ) ,7) ) ) ,4,6) ,12) ) ) +transpose(((step(((transpose(((transpose((((transpose(X,-7) |(transpose(X,-7) +transpose(X,7) ) ) +transpose(transpose((transpose(X,-5) |transpose(X,-7) ) ,4) ,4) ) +transpose(arpeggio(step(X,12) ) ,7) ) ,4) +transpose(((((X+X) +X) +transpose(echo(X,4,6) ,12) ) +transpose(X,12) ) ,12) ) +transpose(echo((echo(shuffle(echo(X,4,6) ) ,4,6) +transpose(((transpose(X,-7) +transpose(X,7) ) +X) ,12) ) ,4,6) ,7) ) ,-5) +transpose(transpose(echo(((shuffle(((arpeggio(((X+transpose(X,7) ) +transpose(step(X,12) ,7) ) ) +transpose((X+X) ,12) ) +((X+transpose(X,7) ) +transpose(((X+transpose(echo(X,4,6) ,4) ) +transpose(step(X,12) ,7) ) ,7) ) ) ) +transpose((((transpose(step(X,12) ,-7) +echo(X,4,6) ) +transpose(step(((X+transpose(X,7) ) +transpose((arpeggio(X) +transpose(step(X,12) ,7) ) ,7) ) ,12) ,4) ) +transpose((transpose(step(echo(X,4,6) ,12) ,-7) |transpose((X+X) ,-5) ) ,7) ) ,4) ) +transpose(transpose((((step(transpose(echo(X,4,6) ,-7) ,12) +transpose(transpose(arpeggio(X) ,-5) ,4) ) +transpose((X+transpose(X,-7) ) ,7) ) +transpose(echo((step((X+transpose(X,12) ) ,12) +(X+transpose((X|X) ,12) ) ) ,4,6) ,12) ) ,4) ,7) ) ,4,6) ,4) ,7) ) +transpose((shuffle(((((X+transpose(X,7) ) +transpose(shuffle(X) ,4) ) +transpose(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ,7) ) +transpose((step(echo(X,4,6) ,12) +transpose(X,7) ) ,12) ) ) +transpose((transpose(((step(step(((X+transpose(transpose(X,-7) ,4) ) +transpose(X,7) ) ,12) ,12) +transpose((transpose((((X+transpose(X,4) ) +transpose(X,7) ) +transpose((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(X,12) ) ,7) ) ,4) +transpose((shuffle(echo(X,4,6) ) +step((shuffle(X) +transpose(X,-5) ) ,12) ) ,12) ) ,7) ) +(arpeggio((echo(X,4,6) +transpose((X+X) ,12) ) ) +transpose(transpose(transpose(X,-5) ,-7) ,7) ) ) ,4) +(transpose(((step(X,12) +transpose(((transpose(X,4) +(X|X) ) +transpose(arpeggio(transpose(X,4) ) ,12) ) ,7) ) +transpose((shuffle((X|X) ) +transpose(transpose((((X+transpose(X,12) ) +transpose(shuffle(X) ,4) ) +transpose(echo(X,4,6) ,7) ) ,-7) ,7) ) ,7) ) ,4) +transpose((transpose(step(((((X+transpose(X,12) ) +transpose(X,12) ) +transpose((X+transpose(X,12) ) ,4) ) +transpose(transpose(X,4) ,7) ) ,12) ,4) +transpose(transpose((((X+transpose(X,7) ) +transpose(arpeggio(X) ,4) ) +transpose(X,7) ) ,4) ,12) ) ,12) ) ) ,12) ) ,12) ) ,12) +(((transpose((arpeggio((((echo(X,4,6) +(X+transpose((arpeggio(X) +transpose(X,7) ) ,12) ) ) |((((echo(step(X,12) ,4,6) +transpose(transpose((X+transpose(X,7) ) ,4) ,7) ) +transpose((((X+transpose(X,4) ) +transpose(X,7) ) +arpeggio(X) ) ,7) ) +transpose(shuffle(transpose(arpeggio(X) ,-7) ) ,12) ) +arpeggio(transpose((((X+transpose(X,12) ) +transpose((X+transpose(X,12) ) ,4) ) +transpose(arpeggio(X) ,7) ) ,-5) ) ) ) |step(transpose(((transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) +transpose((X|(X+X) ) ,12) ) +transpose(((X+transpose(X,7) ) +transpose(X,12) ) ,-5) ) ,-5) ,12) ) ) +transpose(((echo(transpose(X,4) ,4,6) +transpose((transpose(arpeggio(step(X,12) ) ,-5) +transpose(((X|((X+transpose((X+transpose(X,7) ) ,4) ) +transpose(arpeggio(X) ,7) ) ) +transpose((((shuffle(X) +transpose((step(X,12) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ) ,12) ) +transpose(echo(echo(transpose(X,-7) ,4,6) ,4,6) ,7) ) +transpose(step(transpose(X,-7) ,12) ,12) ) ,7) ) ,7) ) ,4) ) +transpose(shuffle((transpose(((((X+transpose(X,7) ) +transpose(X,-7) ) +transpose(transpose(X,-7) ,12) ) +transpose(arpeggio(shuffle(transpose(X,-7) ) ) ,12) ) ,-5) +transpose((((((X+transpose(X,7) ) +transpose(((transpose(X,-5) +transpose(arpeggio(X) ,4) ) +transpose(transpose(X,4) ,7) ) ,4) ) +transpose(transpose(X,4) ,7) ) +transpose(shuffle(shuffle(echo(((X+transpose(X,4) ) +transpose(X,7) ) ,4,6) ) ) ,4) ) +transpose(transpose((X+X) ,4) ,7) ) ,7) ) ) ,7) ) ,12) ) ,-5) +transpose((transpose(echo(echo((transpose(arpeggio(((X+transpose(X,12) ) +transpose(transpose(X,-7) ,7) ) ) ,4) +transpose(((arpeggio(X) +transpose((echo(X,4,6) +transpose(X,7) ) ,12) ) +transpose(shuffle(X) ,7) ) ,12) ) ,4,6) ,4,6) ,-7) |(((((((echo(X,4,6) +transpose(echo(((X|X) +transpose(echo(X,4,6) ,7) ) ,4,6) ,4) ) +transpose(((X+transpose(X,12) ) +X) ,7) ) +transpose((echo(X,4,6) |((X+transpose(X,7) ) |X) ) ,12) ) +transpose((step(X,12) |transpose(step((step((arpeggio(X) +transpose((X+transpose(X,7) ) ,7) ) ,12) +transpose(arpeggio(transpose(X,4) ) ,12) ) ,12) ,-5) ) ,12) ) +transpose(transpose(((echo((transpose(step(X,12) ,-7) +transpose((((X+transpose(X,12) ) +transpose(X,12) ) +transpose((X+transpose(X,7) ) ,12) ) ,7) ) ,4,6) +transpose(shuffle((X+transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ) ) ,4) ) +transpose((((step(shuffle(X) ,12) |(step(transpose(X,-7) ,12) +transpose((echo(X,4,6) +transpose(echo(transpose(X,-7) ,4,6) ,12) ) ,12) ) ) +transpose((step(((transpose(X,-5) |echo(X,4,6) ) +transpose(((X+transpose(X,7) ) +transpose(X,7) ) ,7) ) ,12) +transpose(((((X+transpose(X,12) ) +(((X+transpose(X,4) ) +transpose(X,7) ) +((X+transpose(X,4) ) +transpose(X,7) ) ) ) +transpose(step(transpose(X,4) ,12) ,4) ) +transpose(((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(X,4) ) +transpose(echo(X,4,6) ,7) ) ,7) ) ,7) ) ,4) ) +transpose(shuffle(step(shuffle(X) ,12) ) ,7) ) ,7) ) ,-7) ,4) ) +transpose((echo(((step((X+X) ,12) +transpose(echo(((X+transpose(X,4) ) +transpose(X,7) ) ,4,6) ,4) ) +transpose(step((X+transpose(shuffle(X) ,7) ) ,12) ,7) ) ,4,6) +transpose(step(((step(transpose(transpose((X|X) ,-7) ,4) ,12) +transpose(((X+transpose(X,7) ) +transpose(arpeggio((X+transpose(X,12) ) ) ,12) ) ,4) ) +transpose(((arpeggio((step(X,12) +transpose(transpose(X,-7) ,7) ) ) +transpose(step(X,12) ,7) ) +transpose((transpose(shuffle(X) ,4) +transpose(arpeggio((X+transpose(X,12) ) ) ,12) ) ,7) ) ,7) ) ,12) ,7) ) ,7) ) +transpose((((transpose((shuffle((echo(X,4,6) |((X+transpose(X,4) ) +transpose(X,7) ) ) ) +transpose((X+transpose((X+X) ,7) ) ,12) ) ,-5) |echo(transpose((shuffle(shuffle(step(X,12) ) ) |(echo((X+transpose(X,7) ) ,4,6) |(step(X,12) +transpose((X|X) ,12) ) ) ) ,-5) ,4,6) ) +transpose(((arpeggio((((((shuffle(X) +transpose(X,12) ) +transpose(step(X,12) ,4) ) +transpose((X|X) ,7) ) +transpose(step((X|X) ,12) ,4) ) +transpose(transpose(X,-7) ,7) ) ) +transpose((transpose(echo((X+transpose(X,7) ) ,4,6) ,4) |step((((arpeggio(X) +transpose(echo((X+transpose(X,12) ) ,4,6) ,7) ) +transpose(step(echo(transpose(X,4) ,4,6) ,12) ,4) ) +transpose(echo(arpeggio(X) ,4,6) ,7) ) ,12) ) ,12) ) +transpose(arpeggio(transpose((((shuffle((X+X) ) +transpose(step(X,12) ,12) ) +((shuffle(X) +transpose(X,12) ) +transpose(echo(X,4,6) ,12) ) ) +transpose(transpose(step(X,12) ,-7) ,12) ) ,-5) ) ,12) ) ,4) ) +transpose(((transpose(arpeggio(transpose((((X+X) +transpose(X,4) ) +transpose(X,7) ) ,4) ) ,4) +transpose((transpose((echo((((X+transpose(X,12) ) +transpose(arpeggio(X) ,4) ) +transpose((X+X) ,7) ) ,4,6) +transpose(arpeggio((X+transpose(transpose(X,4) ,12) ) ) ,7) ) ,4) +arpeggio(step(((X+transpose(transpose(transpose(X,4) ,-7) ,4) ) +transpose(((transpose(X,-7) +transpose(transpose(X,4) ,4) ) +transpose(step(X,12) ,7) ) ,7) ) ,12) ) ) ,12) ) +transpose(transpose(step((transpose(X,-5) +transpose((X|transpose(X,4) ) ,12) ) ,12) ,-7) ,7) ) ,7) ) ,7) ) ) ,12) ) +transpose(transpose(((arpeggio(((X+arpeggio(((X+transpose(X,4) ) +transpose(X,7) ) ) ) +transpose((transpose((((X+X) +transpose(arpeggio(X) ,4) ) +transpose(X,7) ) ,4) |((X+transpose(X,4) ) +transpose(X,7) ) ) ,7) ) ) +transpose(((step(step((echo(X,4,6) +transpose((X+transpose(X,12) ) ,12) ) ,12) ,12) +transpose(echo(shuffle(echo(X,4,6) ) ,4,6) ,-5) ) |arpeggio(((transpose(shuffle((X+transpose(X,7) ) ) ,-7) +transpose((X+transpose(echo(transpose(X,-5) ,4,6) ,7) ) ,4) ) +transpose((shuffle((X+transpose(X,7) ) ) |(X|X) ) ,7) ) ) ) ,4) ) +transpose(echo((arpeggio(transpose(echo(X,4,6) ,4) ) +echo(step(echo(arpeggio((transpose(X,-7) +transpose(X,7) ) ) ,4,6) ,12) ,4,6) ) ,4,6) ,7) ) ,-5) ,4) ) +transpose(step(shuffle(shuffle(shuffle(((echo(((X+transpose(X,4) ) +transpose(X,7) ) ,4,6) +transpose((transpose(transpose((X|X) ,-7) ,4) +transpose(((X+X) +transpose((echo(X,4,6) +transpose((X+transpose(X,7) ) ,12) ) ,7) ) ,7) ) ,12) ) +transpose(((echo(transpose((X|X) ,-5) ,4,6) +transpose(echo(echo((((X+transpose(X,4) ) +transpose((X+transpose(X,7) ) ,7) ) |(transpose(X,-7) |shuffle(X) ) ) ,4,6) ,4,6) ,12) ) +transpose((((shuffle(((echo(X,4,6) |shuffle(X) ) +transpose(step(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ,7) ) ) +transpose((((step(step(X,12) ,12) +((X+X) +(X+transpose(X,12) ) ) ) +transpose(transpose((X+transpose(shuffle(X) ,12) ) ,4) ,4) ) +transpose(transpose(X,4) ,7) ) ,4) ) +transpose((shuffle(shuffle(X) ) |X) ,7) ) +transpose(((shuffle(shuffle(echo((X+X) ,4,6) ) ) +transpose(((transpose((X+transpose(X,12) ) ,-7) +transpose(((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(X,4) ) +transpose((X+transpose(X,7) ) ,7) ) ,4) ) +transpose(transpose(X,-7) ,7) ) ,4) ) +transpose((shuffle(arpeggio(shuffle(X) ) ) +transpose(((X+transpose(X,12) ) +transpose(X,12) ) ,7) ) ,7) ) ,12) ) ,12) ) ,12) ) ) ) ) ,12) ,7) ) ) |(transpose(echo((arpeggio(echo(step(X,12) ,4,6) ) +arpeggio((echo(((step(step(echo(X,4,6) ,12) ,12) +transpose(shuffle(step(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ) ,4) ) +transpose((((X+transpose(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,-7) ,7) ) +transpose((X+transpose((X+transpose(X,12) ) ,12) ) ,7) ) +((X+transpose(X,12) ) +echo(X,4,6) ) ) ,7) ) ,4,6) +transpose((step(((transpose(transpose(X,4) ,-5) +transpose((X+transpose(X,12) ) ,12) ) +transpose(transpose(arpeggio(X) ,4) ,7) ) ,12) +transpose(((transpose(transpose((X+transpose(X,7) ) ,4) ,4) +transpose(((transpose((X+transpose(X,7) ) ,-5) +transpose((X|step(X,12) ) ,7) ) +transpose(transpose(((X+transpose(arpeggio(X) ,4) ) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,7) ) ,4) ,7) ) ,4) ) +transpose(echo(((transpose(X,-5) +transpose(arpeggio(shuffle(X) ) ,7) ) +transpose(step(transpose(X,-5) ,12) ,7) ) ,4,6) ,7) ) ,12) ) ,12) ) ) ) ,4,6) ,-7) +transpose(step(arpeggio(transpose((((transpose((((((step(X,12) +transpose(X,7) ) +transpose(shuffle(X) ,4) ) +transpose(echo(X,4,6) ,7) ) +(step(X,12) +transpose(step(X,12) ,12) ) ) +((shuffle(X) +transpose(X,12) ) |shuffle(((transpose(X,4) +transpose(X,4) ) +transpose((X+transpose(X,12) ) ,7) ) ) ) ) ,4) +transpose(((echo((shuffle(arpeggio(X) ) +transpose(transpose(step(X,12) ,-7) ,7) ) ,4,6) +transpose(arpeggio(transpose(((X+transpose(X,7) ) |X) ,-7) ) ,4) ) +transpose(((echo((X+transpose(X,12) ) ,4,6) |arpeggio(X) ) +transpose((shuffle(X) +transpose(step(step(X,12) ,12) ,7) ) ,12) ) ,7) ) ,7) ) +transpose(((transpose(step(((X+transpose(X,12) ) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,7) ) ,12) ,-7) +transpose(shuffle(echo(transpose(X,-5) ,4,6) ) ,7) ) +transpose((((transpose((X+transpose(X,12) ) ,-5) +transpose(((shuffle(shuffle(X) ) +transpose(echo(X,4,6) ,4) ) +transpose((X+X) ,7) ) ,12) ) +transpose(transpose((step((X+transpose(X,12) ) ,12) +transpose(X,12) ) ,-7) ,4) ) +transpose((((step(X,12) +transpose(step(X,12) ,12) ) +transpose(X,4) ) +transpose(echo(echo(X,4,6) ,4,6) ,7) ) ,7) ) ,12) ) ,4) ) +transpose((((arpeggio(transpose(X,4) ) +shuffle(transpose(X,-7) ) ) |echo(echo(((X|X) +transpose(X,7) ) ,4,6) ,4,6) ) +transpose((((((((X+transpose(X,7) ) +transpose((X+transpose(X,7) ) ,4) ) +transpose((X+transpose(X,7) ) ,7) ) |X) +step(X,12) ) +transpose(shuffle(((X+X) +transpose(arpeggio(X) ,7) ) ) ,4) ) +transpose(transpose(shuffle(X) ,-5) ,7) ) ,7) ) ,7) ) ,4) ) ,12) ,7) ) ) ,12) )
random seed used was 72222346

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