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(arpeggio((((echo(transpose(transpose(transpose(X,4) ,4) ,4) ,4,6) +transpose(transpose(arpeggio(((X+transpose(X,7) ) |(X+transpose(X,12) ) ) ) ,4) ,7) ) +transpose((transpose((transpose((X+transpose(X,7) ) ,-5) +(X+(X+transpose(X,12) ) ) ) ,-5) +transpose(((echo((X|X) ,4,6) +echo(X,4,6) ) +transpose(step(transpose((X+transpose(X,12) ) ,4) ,12) ,12) ) ,7) ) ,12) ) +transpose((transpose(transpose((transpose(X,-7) |X) ,4) ,-7) +transpose(step((echo(X,4,6) +transpose(shuffle(X) ,4) ) ,12) ,7) ) ,7) ) ) ) ,-5) ,12) +transpose((((shuffle(transpose(step(transpose(echo(arpeggio((((X+transpose(arpeggio(X) ,7) ) +transpose(((X+transpose(X,4) ) +transpose(transpose(X,-5) ,7) ) ,7) ) +transpose((step(X,12) +((X+transpose(X,4) ) +transpose(X,7) ) ) ,12) ) ) ,4,6) ,-7) ,12) ,-7) ) +transpose(((transpose((((transpose((X+transpose(X,7) ) ,-5) +transpose(step(transpose(X,-7) ,12) ,12) ) +transpose(echo(X,4,6) ,12) ) +((arpeggio(((X+transpose(X,12) ) +transpose(transpose(X,-7) ,12) ) ) +transpose(transpose(X,-5) ,12) ) +transpose(transpose(transpose(X,-7) ,-5) ,12) ) ) ,4) +transpose((echo(transpose(((step(arpeggio(X) ,12) +transpose(((shuffle(((X+X) |X) ) +transpose(transpose(((X+transpose(X,7) ) |((X+transpose(X,4) ) +transpose(step(X,12) ,7) ) ) ,-5) ,4) ) +transpose(((X+arpeggio(X) ) +(arpeggio(X) |(X+transpose(X,7) ) ) ) ,7) ) ,4) ) +transpose(arpeggio(transpose((((X+(X+transpose(X,7) ) ) +transpose(X,4) ) +step(X,12) ) ,-5) ) ,7) ) ,-7) ,4,6) +transpose((((((X+X) +transpose(transpose((X+transpose(X,7) ) ,-5) ,12) ) +X) +transpose(transpose(transpose(transpose(X,-7) ,-7) ,-7) ,7) ) +transpose(transpose((transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,-7) +transpose(transpose((X|X) ,4) ,12) ) ,-5) ,4) ) ,-5) ) ,7) ) |(transpose((arpeggio(transpose(transpose(((((X+transpose(X,7) ) +X) +transpose((transpose(X,-7) +transpose(X,12) ) ,7) ) |(X+transpose(X,12) ) ) ,4) ,-7) ) +arpeggio((echo(X,4,6) +transpose(X,-5) ) ) ) ,4) +transpose(transpose(((X+transpose(X,12) ) |step(transpose(X,-7) ,12) ) ,-7) ,-5) ) ) ,7) ) +transpose(echo(transpose(transpose(transpose((transpose(echo(((transpose((transpose((step(X,12) |X) ,-7) +transpose(transpose(transpose(transpose(X,-7) ,4) ,4) ,7) ) ,-5) +transpose(transpose(transpose(transpose((echo(X,4,6) |arpeggio(X) ) ,4) ,-7) ,-5) ,12) ) |transpose((echo(transpose(transpose(arpeggio(X) ,-5) ,4) ,4,6) |(shuffle((X|X) ) |(((X+X) +((X+X) |shuffle(X) ) ) +(X+X) ) ) ) ,-7) ) ,4,6) ,4) +transpose(echo(transpose(transpose(transpose(step((transpose(transpose(X,-5) ,-5) +(((X+transpose(X,4) ) +transpose(X,7) ) |X) ) ,12) ,-7) ,-7) ,-7) ,4,6) ,4) ) ,-7) ,4) ,-5) ,4,6) ,4) ) +transpose((shuffle(transpose((((transpose(((arpeggio(((shuffle((transpose(X,4) +transpose(X,7) ) ) +transpose(step(X,12) ,7) ) +transpose(X,4) ) ) +transpose(((transpose(((((X+X) +transpose((X+transpose(X,7) ) ,4) ) +transpose(transpose(X,4) ,7) ) +transpose(X,-5) ) ,-5) +transpose((((transpose(X,-5) |shuffle(X) ) +(transpose(X,-7) +transpose(X,12) ) ) +arpeggio(X) ) ,12) ) +transpose((X|(X+transpose(X,-7) ) ) ,4) ) ,7) ) +(transpose(transpose(transpose((X+X) ,-5) ,-5) ,4) +transpose(((transpose(step(((X|X) +transpose((X|X) ,7) ) ,12) ,4) +transpose((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(transpose(shuffle(transpose(X,-5) ) ,-7) ,7) ) ,4) ) +transpose(step(transpose(transpose(X,4) ,-7) ,12) ,7) ) ,7) ) ) ,4) +transpose((transpose(transpose((((arpeggio((X+transpose(X,12) ) ) +transpose(transpose(X,4) ,4) ) +transpose(X,7) ) +transpose(transpose(echo(X,4,6) ,-7) ,12) ) ,-5) ,-5) +transpose(shuffle(transpose(echo(((((X+transpose(X,4) ) +transpose(X,7) ) |(X+X) ) +transpose(transpose(X,4) ,-5) ) ,4,6) ,-5) ) ,12) ) ,4) ) +transpose(step((transpose((((transpose((X|transpose(X,-7) ) ,4) +transpose(transpose(shuffle(X) ,4) ,12) ) +transpose(transpose(X,-7) ,12) ) +transpose((shuffle((X|X) ) +(X|(X+X) ) ) ,-5) ) ,-5) |transpose(((shuffle((echo(transpose(X,4) ,4,6) +(X+X) ) ) +transpose(transpose(echo(arpeggio(X) ,4,6) ,-5) ,12) ) |echo(step(transpose(X,-5) ,12) ,4,6) ) ,-7) ) ,12) ,7) ) +transpose(((transpose((shuffle(((X|X) |(shuffle(X) +arpeggio(X) ) ) ) +(((step(X,12) |X) |(transpose((X+transpose(X,7) ) ,4) +X) ) |((((transpose(X,4) +transpose(((X+transpose(X,12) ) +transpose(transpose(X,-5) ,12) ) ,4) ) +transpose(echo(X,4,6) ,7) ) +transpose(((transpose(X,4) |transpose(X,-5) ) |(X|(X+transpose(X,12) ) ) ) ,4) ) +transpose(transpose((X+transpose(X,12) ) ,-5) ,7) ) ) ) ,-5) +transpose(transpose(shuffle(transpose(transpose(transpose(X,-7) ,-5) ,-5) ) ,-7) ,7) ) +echo((((echo(transpose(transpose(X,-5) ,4) ,4,6) +transpose(((transpose((X+X) ,-5) +X) +(((X+X) +transpose(((shuffle(X) +transpose((X+transpose(X,7) ) ,12) ) +transpose((X|X) ,7) ) ,4) ) +transpose(step(arpeggio(transpose(X,4) ) ,12) ,7) ) ) ,4) ) +transpose(transpose((step(X,12) +transpose(shuffle(transpose((X|X) ,-7) ) ,12) ) ,-7) ,7) ) |((((((X+transpose((X+transpose(X,12) ) ,7) ) +transpose(X,-7) ) +transpose(step(X,12) ,4) ) +transpose((transpose(X,-7) +X) ,7) ) +transpose((step(step((X+X) ,12) ,12) +transpose(transpose(((X+transpose(echo(X,4,6) ,7) ) +transpose(echo(X,4,6) ,12) ) ,-7) ,7) ) ,4) ) +transpose(((transpose((transpose(X,-7) +shuffle(X) ) ,-7) +transpose((X|(X+transpose(X,7) ) ) ,4) ) +transpose(transpose(echo(X,4,6) ,-7) ,7) ) ,7) ) ) ,4,6) ) ,12) ) ,-5) ) |(arpeggio(arpeggio(transpose((((((X+transpose(X,4) ) +transpose(X,7) ) |X) +((X|transpose(X,-5) ) +transpose((X+echo(X,4,6) ) ,12) ) ) +((((X+X) +transpose(shuffle(X) ,4) ) +transpose((X|X) ,7) ) +transpose((step(X,12) +transpose((X+X) ,7) ) ,12) ) ) ,4) ) ) |(transpose(transpose((arpeggio(transpose((X+transpose(X,7) ) ,-5) ) +transpose(transpose(step(transpose(X,-5) ,12) ,-5) ,-7) ) ,-7) ,4) +(transpose(transpose((transpose(((transpose(X,-5) +transpose(((X+transpose(transpose(X,-5) ,4) ) +transpose(transpose(X,-5) ,7) ) ,4) ) +transpose(step(step(X,12) ,12) ,7) ) ,-7) +transpose(step(X,12) ,7) ) ,4) ,-5) |transpose(((((X|X) +transpose(((X|X) +transpose((X+transpose(X,12) ) ,7) ) ,7) ) +((transpose(arpeggio(X) ,-7) +transpose(transpose((X|X) ,4) ,4) ) +transpose(X,7) ) ) |step(echo(((X|X) +transpose(step(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ,12) ) ,4,6) ,12) ) ,-7) ) ) ) ) ,7) ) ,7) ) +transpose((transpose(arpeggio((transpose((shuffle(transpose(transpose((echo(X,4,6) |(X+transpose(X,12) ) ) ,4) ,4) ) +transpose(arpeggio(transpose(((((X+X) +transpose(X,12) ) +transpose(arpeggio(((transpose(X,4) |X) +shuffle(echo(X,4,6) ) ) ) ,4) ) +transpose(echo((((X+X) +transpose(X,4) ) +transpose(X,7) ) ,4,6) ,7) ) ,4) ) ,12) ) ,-7) +transpose(((transpose((transpose(((transpose(X,4) +transpose(X,7) ) +transpose(arpeggio(((X+transpose(X,4) ) +transpose(X,7) ) ) ,7) ) ,-7) +transpose(echo(transpose(echo((X+transpose(X,12) ) ,4,6) ,-5) ,4,6) ,12) ) ,-5) +shuffle((step(arpeggio(arpeggio(transpose((X|X) ,-5) ) ) ,12) +(transpose(transpose((X|X) ,-5) ,4) +transpose(((X+transpose(X,12) ) |((echo(X,4,6) |(X+transpose(X,7) ) ) +transpose((shuffle(X) |X) ,7) ) ) ,7) ) ) ) ) |echo(transpose(((shuffle(step(X,12) ) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,-5) ) |(transpose((X+X) ,-7) +((X|(X+X) ) |transpose(transpose(transpose(X,-5) ,4) ,-7) ) ) ) ,-5) ,4,6) ) ,4) ) ) ,-5) +transpose(transpose(step(transpose(transpose(transpose((((transpose((X+X) ,-7) +transpose(X,-5) ) +transpose(transpose((X+transpose(X,12) ) ,-5) ,7) ) +transpose(transpose(X,-5) ,4) ) ,-5) ,-7) ,4) ,12) ,-7) ,12) ) ,7) ) +transpose(shuffle(echo(transpose((transpose(((transpose(transpose((arpeggio(((arpeggio(echo((shuffle(X) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ) ,4,6) ) +transpose(((X+transpose(X,4) ) +transpose((X+X) ,7) ) ,4) ) +transpose(transpose(X,4) ,7) ) ) +transpose((arpeggio(step(transpose(echo(transpose(transpose((X|X) ,-5) ,-7) ,4,6) ,-5) ,12) ) +transpose((transpose(X,4) +transpose(X,-5) ) ,-7) ) ,12) ) ,-5) ,-5) +transpose(step(transpose(echo(((step((shuffle(X) +transpose(X,7) ) ,12) +transpose((((((X+transpose(X,12) ) |transpose(X,-7) ) |(X+transpose(X,12) ) ) +(transpose(X,-5) +(((transpose(X,-5) +transpose(X,4) ) +transpose(X,7) ) |((X|X) +(X+transpose(X,7) ) ) ) ) ) +transpose((((step(step(X,12) ,12) +transpose(X,-7) ) |echo((X|step(X,12) ) ,4,6) ) |transpose(((echo(X,4,6) +X) |(X+transpose((X+transpose(X,7) ) ,7) ) ) ,4) ) ,12) ) ,-5) ) |(arpeggio((((X+transpose(X,12) ) |X) |(X+X) ) ) +transpose((arpeggio(transpose(X,-5) ) +((((X+transpose(X,12) ) |transpose(X,-5) ) +(X+X) ) +transpose((((X|X) +transpose(X,12) ) +transpose(arpeggio(X) ,7) ) ,7) ) ) ,12) ) ) ,4,6) ,-5) ,12) ,4) ) +transpose(transpose(echo(transpose(transpose((((X+transpose(X,4) ) +transpose(X,-7) ) |((X|transpose(X,-5) ) +echo(X,4,6) ) ) ,4) ,-7) ,4,6) ,-7) ,7) ) ,-7) +(transpose(transpose((transpose(((transpose(((X+transpose(X,4) ) +transpose((X+transpose(X,7) ) ,7) ) ,-5) +transpose(shuffle(transpose((echo(X,4,6) +transpose((X+transpose(X,7) ) ,7) ) ,4) ) ,7) ) +((echo(transpose(transpose(transpose(X,-5) ,4) ,-7) ,4,6) +transpose((echo(((transpose(X,-5) |transpose(X,4) ) +(X|shuffle(X) ) ) ,4,6) +transpose((step(((transpose(X,-5) +transpose((X+X) ,4) ) +transpose((transpose(X,-7) +transpose(transpose(X,4) ,12) ) ,7) ) ,12) |(arpeggio(echo(X,4,6) ) +transpose(X,7) ) ) ,12) ) ,7) ) +(((((((X+transpose(X,4) ) +transpose(X,7) ) |(X+transpose(X,12) ) ) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ) +transpose(((transpose(X,4) +transpose(arpeggio(X) ,7) ) |shuffle(transpose(X,-5) ) ) ,7) ) +(step(echo(((X+transpose(X,4) ) +transpose(X,7) ) ,4,6) ,12) |((X+X) +X) ) ) |shuffle(transpose((transpose(X,-7) +transpose((X|X) ,7) ) ,-7) ) ) ) ) ,4) +transpose((((transpose(transpose((X+X) ,4) ,4) |((((step(X,12) +X) |step(X,12) ) +transpose(transpose(echo(X,4,6) ,-5) ,12) ) +transpose(transpose(step(X,12) ,-5) ,7) ) ) |((step(X,12) +(X+transpose(X,7) ) ) +((X+transpose(X,12) ) +transpose(shuffle(X) ,7) ) ) ) +transpose(transpose(arpeggio(transpose(arpeggio(shuffle(transpose(X,-7) ) ) ,-5) ) ,4) ,-5) ) ,7) ) ,-5) ,-7) +transpose(((transpose(step(((step(step((X|(X|((X+transpose(X,4) ) +transpose(X,7) ) ) ) ,12) ,12) +transpose(((shuffle(X) |(X|X) ) +transpose(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ,4) ) ,-5) ) +((((X|X) |(X+transpose(X,7) ) ) |(transpose((X+transpose(X,12) ) ,-7) |X) ) +transpose(shuffle((transpose(X,-5) +transpose((X+X) ,12) ) ) ,12) ) ) ,12) ,-7) |shuffle((((((shuffle(((X+transpose((X+transpose(X,12) ) ,4) ) +transpose(X,7) ) ) |echo((X|X) ,4,6) ) |arpeggio(transpose((X+X) ,-5) ) ) |transpose((((transpose(X,-5) +transpose(X,4) ) +transpose((X+transpose(X,12) ) ,7) ) +(X+transpose(X,7) ) ) ,4) ) |arpeggio(echo(((((transpose(arpeggio(X) ,4) +transpose(transpose(transpose(X,4) ,-7) ,4) ) +transpose(((X+transpose(arpeggio(X) ,4) ) +transpose((X|X) ,7) ) ,7) ) +transpose((X+transpose(X,7) ) ,4) ) +transpose((transpose((X+transpose(X,7) ) ,4) +transpose(((X+transpose(X,4) ) +transpose(transpose(X,-7) ,7) ) ,7) ) ,7) ) ,4,6) ) ) +transpose((((X+(X+transpose(X,7) ) ) +(arpeggio((((X+transpose(X,4) ) +transpose(step(X,12) ,7) ) |echo(transpose(X,4) ,4,6) ) ) +transpose(transpose((X+transpose(X,12) ) ,-7) ,12) ) ) +echo(transpose(step(arpeggio(X) ,12) ,-5) ,4,6) ) ,12) ) ) ) |transpose((((shuffle(transpose(transpose((X+X) ,-5) ,-5) ) +transpose(echo((((X+transpose(X,4) ) +transpose((X+transpose(X,12) ) ,7) ) +echo(transpose(transpose(X,-7) ,4) ,4,6) ) ,4,6) ,7) ) +(step(transpose((transpose(echo(X,4,6) ,-5) +transpose(transpose(X,4) ,7) ) ,-5) ,12) |((transpose((transpose(transpose(X,4) ,-5) +transpose((X|X) ,12) ) ,-5) |echo(transpose((X|((X+transpose(X,4) ) +transpose(X,7) ) ) ,-5) ,4,6) ) +transpose((transpose((X+X) ,-5) +echo(echo(X,4,6) ,4,6) ) ,-7) ) ) ) +step((echo(transpose(echo(X,4,6) ,4) ,4,6) |echo((transpose(transpose(X,-7) ,4) +(X+(X|X) ) ) ,4,6) ) ,12) ) ,-7) ) ,7) ) ) ,4) ,4,6) ) ,7) )
random seed used was 135748485

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