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:
((arpeggio((echo(((step((shuffle(((transpose(((X+(X+X) ) |(transpose(X,4) |X) ) ,4) +transpose((arpeggio(echo((X+step(X,12) ) ,4,6) ) +transpose(transpose(step(X,12) ,4) ,4) ) ,7) ) |transpose((X+transpose((X+X) ,4) ) ,-5) ) ) +shuffle((((shuffle(echo(X,4,6) ) +transpose(transpose((X|X) ,-7) ,4) ) +transpose(transpose(X,4) ,7) ) +transpose(arpeggio(X) ,12) ) ) ) ,12) +transpose(((transpose((transpose(((transpose(X,-7) +transpose((X+transpose(X,7) ) ,4) ) +transpose(X,7) ) ,-5) |shuffle(arpeggio((shuffle((X|X) ) +transpose((X+transpose((X+transpose(X,12) ) ,12) ) ,12) ) ) ) ) ,-5) |arpeggio(transpose(X,-7) ) ) |shuffle(((transpose(transpose((arpeggio((echo(arpeggio(X) ,4,6) +((X+transpose(X,4) ) +transpose((X+transpose(X,7) ) ,7) ) ) ) +(((X+transpose(X,12) ) +transpose(step(arpeggio(X) ,12) ,12) ) +arpeggio(transpose(X,-5) ) ) ) ,4) ,-7) +transpose(((transpose((step((X+transpose(X,7) ) ,12) +transpose(arpeggio(X) ,12) ) ,4) +(X+transpose(X,7) ) ) +transpose(((step(step(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ,12) |((X|X) |X) ) |transpose((X+echo(transpose(X,-5) ,4,6) ) ,-7) ) ,12) ) ,4) ) +transpose(((((echo((transpose(transpose(X,-5) ,4) +transpose(X,4) ) ,4,6) +shuffle((((((X+transpose(X,4) ) +transpose(X,7) ) +X) |X) +transpose(X,12) ) ) ) +transpose((transpose((shuffle(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,-5) ) |(transpose(X,-7) +transpose(X,12) ) ) ,-7) +transpose(arpeggio(((step(X,12) +transpose(((transpose(X,-7) +transpose(arpeggio(X) ,4) ) +transpose(transpose(X,-5) ,7) ) ,12) ) +transpose(transpose(transpose(X,4) ,4) ,-7) ) ) ,7) ) ,4) ) +transpose(transpose(echo(transpose((X+transpose(X,12) ) ,-5) ,4,6) ,4) ,7) ) +transpose(step(transpose(((X+X) |(((X+transpose(X,12) ) +transpose(transpose(X,-7) ,7) ) +transpose(X,7) ) ) ,-7) ,12) ,12) ) ,7) ) ) ) ,4) ) +transpose(transpose(((((echo(transpose(arpeggio(transpose(transpose(X,-5) ,-5) ) ,4) ,4,6) +transpose(arpeggio(((X|(X+X) ) +(X+transpose(X,-7) ) ) ) ,7) ) +transpose(transpose((transpose(((X+X) +transpose(X,12) ) ,-7) +(transpose((transpose(X,-5) +X) ,-7) +transpose((step(X,12) +transpose(transpose((X+transpose(X,12) ) ,-5) ,12) ) ,12) ) ) ,-5) ,4) ) +transpose((transpose(transpose(shuffle(((X+X) +((X+transpose(X,4) ) +transpose(X,7) ) ) ) ,-7) ,-5) +transpose(((((shuffle(X) +transpose(X,4) ) +transpose(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,-5) ,12) ) +transpose(transpose(transpose(X,-7) ,4) ,4) ) +transpose(((echo((X+transpose(X,12) ) ,4,6) +transpose(transpose(X,4) ,7) ) +transpose((transpose(transpose(X,-5) ,4) +transpose(step((X+transpose(X,7) ) ,12) ,12) ) ,7) ) ,7) ) ,12) ) ,7) ) +transpose((shuffle((transpose(transpose((X|X) ,4) ,4) +transpose((arpeggio(X) +transpose((X|(X|X) ) ,12) ) ,-7) ) ) +transpose((step(((X|X) +transpose(transpose(arpeggio(X) ,4) ,12) ) ,12) +transpose(transpose(((arpeggio(X) +transpose(X,4) ) +transpose(X,7) ) ,-7) ,7) ) ,12) ) ,7) ) ,-7) ,7) ) ,4,6) |transpose((((((transpose(echo((echo((X|X) ,4,6) +(arpeggio(X) +transpose((X+X) ,12) ) ) ,4,6) ,-5) |((transpose((transpose(shuffle(X) ,-7) +transpose(transpose(transpose(X,-5) ,-7) ,7) ) ,4) +transpose(transpose(transpose(X,-5) ,4) ,4) ) +transpose((((X+(arpeggio((X+transpose(X,12) ) ) +transpose((X+transpose(X,12) ) ,7) ) ) +transpose(arpeggio(step(transpose(X,4) ,12) ) ,4) ) +transpose(((transpose(X,-5) |echo((X+X) ,4,6) ) |((X+transpose(X,4) ) +transpose(X,7) ) ) ,7) ) ,7) ) ) +transpose(arpeggio(transpose(transpose((step(echo((arpeggio(X) +(X|(X|X) ) ) ,4,6) ,12) +(((((X+transpose(arpeggio(X) ,12) ) +transpose(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ,4) ) +transpose((X+transpose(X,12) ) ,7) ) +transpose(transpose(transpose(arpeggio(X) ,-5) ,-5) ,4) ) +transpose((X+(X+transpose(X,7) ) ) ,7) ) ) ,4) ,-5) ) ,7) ) |arpeggio((transpose(transpose((((X+transpose(X,12) ) +transpose(X,12) ) +((X|X) |X) ) ,4) ,4) +transpose((((transpose(((step(transpose(X,-7) ,12) +transpose(shuffle(X) ,4) ) +transpose(step(step(X,12) ,12) ,7) ) ,-5) +transpose((((transpose(X,-7) |X) +transpose((((transpose(arpeggio(X) ,-5) |arpeggio((X|X) ) ) +transpose((transpose(X,4) +transpose(X,-5) ) ,4) ) +transpose(X,7) ) ,4) ) +transpose(transpose(arpeggio(X) ,-7) ,7) ) ,4) ) +transpose(((transpose(X,-7) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ) +transpose((X+X) ,7) ) ,7) ) |(transpose(transpose(((transpose((X+transpose(X,12) ) ,-5) +transpose((transpose(X,4) +X) ,4) ) +transpose(transpose(X,-5) ,7) ) ,4) ,-5) +transpose(transpose(step((X+transpose(X,7) ) ,12) ,4) ,7) ) ) ,12) ) ) ) +transpose(transpose(step((transpose(((transpose(((transpose(X,4) +transpose(shuffle(X) ,4) ) +transpose(transpose(X,-5) ,7) ) ,-5) +transpose(step(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ,-5) ) |(shuffle(step(X,12) ) +(echo((X|X) ,4,6) +(X|transpose(X,-5) ) ) ) ) ,4) +transpose(transpose(transpose(transpose(((X|X) +arpeggio(X) ) ,-7) ,-7) ,4) ,7) ) ,12) ,-5) ,4) ) +transpose(arpeggio(arpeggio(((echo((step(transpose(X,4) ,12) |transpose(X,4) ) ,4,6) +transpose(arpeggio(((X+X) |transpose(X,-5) ) ) ,4) ) +transpose(transpose((X|X) ,-5) ,7) ) ) ) ,7) ) ,-7) ) ) +transpose((transpose(transpose((((transpose(transpose(transpose(X,-5) ,-5) ,4) +transpose(((transpose(X,4) +transpose(arpeggio((X+X) ) ,4) ) +transpose(step(shuffle(X) ,12) ,7) ) ,12) ) +transpose(transpose((step(shuffle(X) ,12) |shuffle((X+transpose(X,12) ) ) ) ,-7) ,7) ) +transpose((transpose(step(transpose(transpose(transpose(X,-5) ,-7) ,-7) ,12) ,-5) +shuffle(transpose(transpose(X,4) ,-7) ) ) ,12) ) ,4) ,4) +shuffle(((((((shuffle((transpose(transpose(X,4) ,-7) +(step(X,12) |(X|X) ) ) ) +transpose(transpose(transpose(transpose(transpose((transpose(transpose(X,4) ,-7) +(step(X,12) +transpose(echo(X,4,6) ,12) ) ) ,-7) ,-7) ,4) ,-5) ,7) ) |shuffle(((transpose(transpose(shuffle(transpose(X,-5) ) ,4) ,4) +transpose(transpose(((transpose(X,4) +transpose(X,7) ) +transpose(transpose((X|X) ,-7) ,12) ) ,-7) ,4) ) +transpose(shuffle((arpeggio((X+transpose(X,7) ) ) +(((transpose(X,-7) +transpose(transpose(X,-5) ,4) ) +transpose((X+transpose(X,12) ) ,7) ) |transpose(X,-5) ) ) ) ,7) ) ) ) |(transpose(transpose((((transpose(X,-5) +transpose(((transpose(X,4) +transpose(X,4) ) +transpose(transpose(X,-7) ,12) ) ,7) ) |step((((X+transpose((X+X) ,12) ) +transpose(transpose(transpose(X,-5) ,-5) ,4) ) +transpose(step(X,12) ,7) ) ,12) ) +step(echo(((((X+transpose(X,7) ) +transpose(X,4) ) +transpose(transpose(X,4) ,12) ) +transpose(X,4) ) ,4,6) ,12) ) ,-5) ,4) +transpose(transpose((step((transpose(transpose(X,4) ,4) +transpose(transpose((X|X) ,-5) ,12) ) ,12) +((transpose(step(X,12) ,4) +transpose(transpose((transpose(X,-7) +transpose(transpose(transpose(X,-7) ,4) ,12) ) ,-7) ,4) ) +transpose(transpose(X,-7) ,7) ) ) ,4) ,-7) ) ) +transpose(((((((transpose(transpose(transpose(X,-5) ,-5) ,4) +step(arpeggio(arpeggio(X) ) ,12) ) +transpose((shuffle(arpeggio(X) ) +transpose((X+transpose(X,-5) ) ,12) ) ,12) ) |transpose(arpeggio(transpose(step((X+transpose(X,12) ) ,12) ,-5) ) ,-7) ) |transpose((((transpose(X,-7) +transpose(transpose(shuffle(X) ,-5) ,7) ) +transpose(transpose(step((X+X) ,12) ,-7) ,-5) ) +transpose(((transpose(X,-5) +transpose(((X+transpose(X,7) ) +(transpose(X,-5) +X) ) ,7) ) +transpose((echo(transpose(step(transpose(X,-5) ,12) ,-7) ,4,6) +transpose((((X+(X|X) ) +transpose(X,4) ) +transpose(transpose(transpose((X|X) ,4) ,4) ,12) ) ,12) ) ,12) ) ,12) ) ,-5) ) |transpose((step(transpose(echo(transpose(X,-5) ,4,6) ,-7) ,12) +transpose((((transpose(X,4) +transpose(X,-5) ) +transpose(X,7) ) +echo((X|X) ,4,6) ) ,-5) ) ,4) ) |echo(arpeggio(((((X+transpose(X,12) ) +(X+transpose(X,7) ) ) +arpeggio(X) ) |transpose(X,-7) ) ) ,4,6) ) ,4) ) +transpose(transpose((transpose(transpose(((transpose(((echo((transpose(X,-7) |X) ,4,6) |(transpose(X,-7) |((((step(X,12) +transpose(X,4) ) +transpose(transpose((X+transpose(X,12) ) ,-5) ,4) ) +transpose(X,7) ) +transpose((transpose(X,-7) +transpose(transpose(X,-7) ,12) ) ,7) ) ) ) |step((transpose(X,4) +(X+transpose(X,7) ) ) ,12) ) ,-5) +transpose(((transpose((transpose(transpose(X,-7) ,-7) |step(transpose(((X+transpose(X,7) ) +(X+transpose(X,12) ) ) ,-5) ,12) ) ,-7) +transpose((((transpose((shuffle(X) +transpose((X+X) ,-5) ) ,-5) |transpose(((transpose(X,-5) +transpose(X,4) ) +transpose(((transpose(X,-7) +transpose((X|X) ,4) ) +transpose(X,7) ) ,7) ) ,4) ) +transpose(((X+transpose(X,-7) ) +transpose((shuffle((transpose(X,-7) +transpose((X+transpose(X,12) ) ,7) ) ) +echo(((shuffle((X+X) ) +transpose(transpose(X,-5) ,4) ) +transpose(transpose((X+transpose(X,7) ) ,-7) ,7) ) ,4,6) ) ,7) ) ,4) ) +transpose(transpose((echo((X|X) ,4,6) |transpose((X+X) ,-7) ) ,-5) ,7) ) ,4) ) +transpose(transpose(((transpose((X|(transpose(X,4) +transpose(shuffle(X) ,12) ) ) ,-5) +transpose(step((step(shuffle(step(X,12) ) ,12) +step(X,12) ) ,12) ,4) ) +transpose(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ,7) ) ,4) ,7) ) ,4) ) +transpose((transpose((transpose(X,4) +transpose((X+transpose(echo(X,4,6) ,12) ) ,7) ) ,4) +transpose(((arpeggio(arpeggio(X) ) +(((X+X) +transpose(transpose(X,-5) ,4) ) +transpose((X|X) ,7) ) ) +transpose(step(echo(X,4,6) ,12) ,7) ) ,7) ) ,7) ) ,-5) ,4) |((transpose(echo((X|X) ,4,6) ,-7) +(transpose((echo(echo(X,4,6) ,4,6) +transpose((X+transpose(((X+X) |transpose(X,-5) ) ,7) ) ,4) ) ,4) +transpose(((((((((X+transpose(transpose(X,-5) ,4) ) +transpose(transpose(arpeggio(X) ,-7) ,7) ) |echo(X,4,6) ) +transpose(transpose(transpose(transpose(step(X,12) ,-5) ,-7) ,-7) ,4) ) +transpose((((X|X) +transpose(((transpose(X,-5) +transpose(X,7) ) +transpose(transpose(X,-5) ,7) ) ,4) ) +transpose((step(X,12) +((X|X) |(X+X) ) ) ,7) ) ,7) ) +transpose(step(transpose(X,-5) ,12) ,12) ) +transpose(((echo(transpose(step((X|X) ,12) ,-7) ,4,6) +transpose((X|(echo(echo(X,4,6) ,4,6) +transpose((X+(X+transpose(X,12) ) ) ,7) ) ) ,12) ) +transpose(transpose((transpose((X|X) ,4) +transpose(transpose(transpose(X,-7) ,4) ,7) ) ,-7) ,7) ) ,4) ) +transpose(transpose(((transpose(step(X,12) ,-5) +transpose((transpose(transpose(X,4) ,-7) |X) ,4) ) +transpose(transpose((transpose(X,-7) |X) ,4) ,7) ) ,4) ,7) ) ,7) ) ) +transpose(transpose(step(transpose(X,4) ,12) ,-7) ,12) ) ) ,4) ,7) ) |(transpose(echo((((((transpose(shuffle((transpose(transpose(X,-5) ,4) +(X+transpose(X,12) ) ) ) ,4) +transpose(transpose(((X|X) |X) ,-7) ,12) ) +transpose(((transpose((((X+X) +(X+transpose(X,12) ) ) |(((X+transpose(X,4) ) +transpose(X,7) ) |transpose(X,4) ) ) ,4) +transpose(echo(echo(((X+transpose(X,12) ) +((X+transpose(X,4) ) +transpose(X,7) ) ) ,4,6) ,4,6) ,12) ) |step((transpose(X,4) +transpose(X,12) ) ,12) ) ,12) ) +transpose((shuffle(((arpeggio(((X+transpose((X|X) ,4) ) +transpose((X+transpose(X,12) ) ,7) ) ) +transpose((transpose((X+transpose(X,12) ) ,4) +transpose((echo(shuffle(X) ,4,6) +transpose(step(X,12) ,4) ) ,12) ) ,4) ) +transpose(((X|step(X,12) ) +(transpose(X,4) |X) ) ,7) ) ) |transpose(echo((X+X) ,4,6) ,-5) ) ,4) ) +transpose((transpose(transpose(transpose(X,-7) ,-7) ,4) +step(transpose(echo(X,4,6) ,4) ,12) ) ,7) ) |echo((((X|(X+X) ) |transpose(echo(X,4,6) ,4) ) |transpose(transpose(X,-7) ,4) ) ,4,6) ) ,4,6) ,4) |((((transpose(transpose(X,-7) ,4) |transpose((((X|X) +transpose((X+transpose(X,7) ) ,4) ) +transpose(X,7) ) ,-7) ) |(arpeggio(step((X|X) ,12) ) +transpose((((((X|transpose(X,-5) ) +transpose(shuffle(transpose(X,-5) ) ,4) ) +transpose((arpeggio(X) +X) ,7) ) +(echo(X,4,6) +shuffle(X) ) ) +transpose(echo((X+transpose(transpose(X,4) ,12) ) ,4,6) ,7) ) ,12) ) ) +transpose((((shuffle(((X|X) +transpose((((X+transpose(X,12) ) +transpose(transpose(X,-5) ,4) ) +transpose((X+transpose(X,12) ) ,7) ) ,12) ) ) +transpose(arpeggio(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,-5) ) ,12) ) +transpose(transpose(transpose((shuffle(X) +transpose(transpose(X,4) ,7) ) ,-7) ,-5) ,7) ) +transpose((transpose(((transpose(X,-5) +step(X,12) ) +transpose(((X|X) +X) ,7) ) ,-7) |((echo(X,4,6) +transpose(arpeggio(((X+transpose(X,12) ) +transpose(X,-7) ) ) ,4) ) +transpose((transpose(X,4) |step(X,12) ) ,7) ) ) ,-5) ) ,12) ) |transpose((echo(transpose(transpose(transpose((X|X) ,-5) ,-7) ,4) ,4,6) |transpose(transpose(step(X,12) ,-7) ,-7) ) ,4) ) ) ) ) ) ,4) ) +transpose(transpose(transpose(transpose(((step((((X+X) +transpose(X,12) ) |((X|(X+transpose(X,12) ) ) +transpose(shuffle(X) ,7) ) ) ,12) +transpose((step(X,12) +transpose(transpose(X,-7) ,-7) ) ,7) ) +transpose(transpose((transpose(X,4) |X) ,4) ,-7) ) ,-7) ,-5) ,-7) ,7) )
random seed used was 238191166

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