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 18 generations the expression "X" became this:
((((arpeggio((shuffle((((shuffle(transpose((X|X) ,-7) ) +(step(transpose(transpose((X|(X+X) ) ,-7) ,4) ,12) +transpose(step((transpose(X,-7) |X) ,12) ,12) ) ) +transpose(shuffle(X) ,-5) ) +transpose((arpeggio(transpose(transpose((X+transpose(X,7) ) ,-7) ,-7) ) +transpose((((shuffle(transpose(((transpose(X,-5) |shuffle(X) ) +transpose(shuffle(transpose(X,-7) ) ,7) ) ,-7) ) +transpose(step(((arpeggio(X) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,7) ) |echo(X,4,6) ) ,12) ,4) ) +transpose(((step((arpeggio(X) +(X+X) ) ,12) +transpose(echo(((X+transpose(X,4) ) +transpose(X,7) ) ,4,6) ,-7) ) +transpose(transpose((arpeggio((transpose(X,4) +transpose(X,12) ) ) |transpose(X,-7) ) ,4) ,12) ) ,7) ) +shuffle(transpose(X,4) ) ) ,12) ) ,4) ) ) |step(((((((arpeggio(transpose((X|X) ,-5) ) +transpose((transpose(transpose(X,4) ,-5) +transpose(transpose(X,4) ,12) ) ,12) ) +transpose((((X|X) |transpose((X+X) ,-7) ) +transpose(((X+transpose(X,12) ) |X) ,12) ) ,7) ) |((echo(transpose(X,4) ,4,6) |(transpose(X,-7) |arpeggio(echo(X,4,6) ) ) ) +transpose(transpose(transpose(transpose((transpose(X,4) |(X|X) ) ,-5) ,-7) ,4) ,7) ) ) +transpose(transpose(transpose(arpeggio((transpose(((X+((X+transpose(X,4) ) +transpose((X+transpose(X,12) ) ,7) ) ) |(((transpose(X,4) +transpose(X,4) ) +transpose((X|X) ,7) ) |(X+transpose((X+transpose(X,7) ) ,7) ) ) ) ,4) +transpose(transpose((((X|X) |arpeggio(step(X,12) ) ) +shuffle(shuffle(X) ) ) ,-5) ,7) ) ) ,-5) ,4) ,4) ) +transpose(transpose(arpeggio(transpose((X|X) ,4) ) ,-7) ,7) ) +transpose((transpose((shuffle(transpose(transpose((X+X) ,-5) ,4) ) +transpose(((transpose(X,-5) +transpose((X|X) ,12) ) |transpose(X,-7) ) ,12) ) ,4) +transpose(((transpose(((X+transpose(X,7) ) |shuffle(X) ) ,-5) +((echo(shuffle(transpose(X,-7) ) ,4,6) +transpose(transpose(shuffle(X) ,-5) ,-5) ) +shuffle(transpose(transpose(shuffle(X) ,-5) ,4) ) ) ) +transpose(((((X+shuffle(X) ) +shuffle(X) ) +transpose(transpose((((((X+X) +transpose(transpose(X,-5) ,12) ) +transpose(X,4) ) +transpose(transpose(X,4) ,7) ) +transpose((X+transpose((step(X,12) +((X+transpose(X,4) ) +transpose(X,7) ) ) ,7) ) ,12) ) ,4) ,4) ) +transpose(transpose((step(echo(X,4,6) ,12) |(step(transpose(X,-7) ,12) +transpose(((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(echo(X,4,6) ,4) ) +transpose((X+X) ,7) ) ,12) ) ) ,4) ,7) ) ,7) ) ,7) ) ,4) ) ,12) ) ) +(transpose(transpose(transpose(step(transpose(echo(((X|X) |transpose(X,-7) ) ,4,6) ,-7) ,12) ,4) ,-5) ,4) |(echo((X|arpeggio((step((X+X) ,12) +transpose((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ) ,12) ) ) ) ,4,6) +transpose(echo((transpose(shuffle(transpose(step(X,12) ,-5) ) ,4) +(transpose(X,-5) +transpose((X|X) ,-5) ) ) ,4,6) ,12) ) ) ) +transpose(((transpose((((((transpose(transpose(X,-5) ,-7) +arpeggio((X|X) ) ) +transpose((transpose(echo(transpose((shuffle(transpose(X,-7) ) +transpose((step(X,12) +transpose((transpose(X,4) +transpose(X,12) ) ,12) ) ,7) ) ,-7) ,4,6) ,-7) +transpose((((transpose(echo(transpose(X,-5) ,4,6) ,-5) |((transpose(X,4) +transpose(echo(X,4,6) ,4) ) +transpose(transpose((X+X) ,-5) ,7) ) ) +transpose(transpose(transpose(step(X,12) ,-7) ,4) ,7) ) +transpose(((arpeggio(X) +transpose((shuffle(X) +transpose(X,12) ) ,4) ) +transpose(transpose(X,-7) ,7) ) ,12) ) ,4) ) ,4) ) +transpose(transpose((transpose(((X+transpose(transpose((step(X,12) +transpose((X+X) ,12) ) ,-7) ,4) ) +transpose((transpose(X,-5) +transpose(X,-7) ) ,7) ) ,4) |(transpose(((transpose(X,4) +transpose(transpose((X|X) ,-7) ,4) ) +transpose((transpose(X,4) +transpose(X,4) ) ,7) ) ,4) |(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,-5) +transpose(X,-7) ) ) ) ,4) ,7) ) +((((transpose(transpose((arpeggio(X) +transpose(((X|echo(X,4,6) ) +transpose(transpose(X,-7) ,7) ) ,12) ) ,4) ,-7) +transpose(transpose(echo(((echo(arpeggio((X|X) ) ,4,6) +transpose((arpeggio(X) |step(X,12) ) ,12) ) |transpose(((transpose(transpose(X,-5) ,4) +transpose((X|transpose(X,-7) ) ,4) ) +transpose(arpeggio(X) ,7) ) ,-5) ) ,4,6) ,-7) ,4) ) +transpose((((transpose(((X|X) +X) ,-7) |(transpose((X|X) ,-5) +transpose((transpose(X,-5) +transpose(transpose(X,4) ,12) ) ,7) ) ) +transpose((transpose(X,-7) |(X+((X|X) +shuffle(X) ) ) ) ,7) ) +transpose((((echo(((X|X) +transpose(X,4) ) ,4,6) +transpose((arpeggio((X+transpose(X,12) ) ) +(arpeggio(X) +transpose(X,7) ) ) ,4) ) +transpose(echo(transpose(transpose(X,-7) ,4) ,4,6) ,7) ) +transpose(step((transpose(transpose(transpose(X,4) ,-5) ,-7) +transpose(transpose(X,-7) ,12) ) ,12) ,7) ) ,7) ) ,7) ) +transpose(step((X|(step(transpose(X,-7) ,12) |transpose(X,-7) ) ) ,12) ,4) ) +transpose((((arpeggio((step((X+transpose(X,7) ) ,12) +transpose((X|((X+transpose(X,7) ) +transpose(transpose(X,4) ,7) ) ) ,7) ) ) +transpose(transpose(transpose((X+X) ,-5) ,-5) ,7) ) +transpose((transpose(arpeggio(X) ,4) +(((X+transpose(X,7) ) |arpeggio(X) ) |(transpose(echo(transpose(X,4) ,4,6) ,-5) +arpeggio((step(X,12) +transpose((X+transpose(X,7) ) ,12) ) ) ) ) ) ,4) ) +transpose(((echo((echo(((X+transpose(X,4) ) +transpose(X,7) ) ,4,6) |echo(shuffle(X) ,4,6) ) ,4,6) +echo(X,4,6) ) +transpose(X,12) ) ,7) ) ,7) ) ) +(transpose(arpeggio(arpeggio(((transpose((X+transpose(X,7) ) ,4) +transpose(((X+transpose(X,7) ) +((X|X) +transpose(step(X,12) ,12) ) ) ,12) ) +transpose(transpose((transpose(X,-5) |(X|X) ) ,4) ,12) ) ) ) ,-5) +transpose(transpose((echo((((X|X) +transpose(transpose(X,4) ,4) ) +transpose(X,7) ) ,4,6) +transpose(((transpose(transpose(step(X,12) ,-5) ,-5) +transpose((((X|X) +transpose((transpose(X,-7) |transpose(X,-5) ) ,4) ) +transpose((X|X) ,7) ) ,4) ) +transpose(transpose(X,-5) ,7) ) ,4) ) ,-7) ,12) ) ) ,4) +transpose(((transpose(transpose((arpeggio(((arpeggio((X+transpose(step(X,12) ,12) ) ) +transpose(transpose((X+transpose(X,12) ) ,-7) ,7) ) +transpose(echo(echo(((X+X) +transpose(X,12) ) ,4,6) ,4,6) ,7) ) ) |(arpeggio(((transpose((((arpeggio(X) +transpose((X+X) ,4) ) +transpose(X,7) ) +transpose(shuffle(X) ,4) ) ,4) +transpose(transpose((((X+X) +echo(X,4,6) ) |(X+transpose(X,12) ) ) ,-5) ,12) ) +shuffle(transpose((X|X) ,-5) ) ) ) |shuffle(((shuffle(X) |transpose((X+X) ,-5) ) +((transpose(X,-5) +X) +(X+((X+transpose(X,4) ) +transpose(X,7) ) ) ) ) ) ) ) ,-5) ,-5) +shuffle(((transpose((arpeggio((X+X) ) +(((X+transpose(X,4) ) +transpose(X,7) ) +(transpose(X,4) +transpose(X,12) ) ) ) ,-7) +((step(step((X|X) ,12) ,12) +transpose(((transpose(X,-7) |shuffle(arpeggio(X) ) ) |shuffle((((X+transpose(X,4) ) +transpose(transpose(X,4) ,7) ) +((X+transpose(X,4) ) +transpose(X,7) ) ) ) ) ,4) ) +transpose(transpose(((((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(step(X,12) ,4) ) +transpose(X,7) ) +transpose(arpeggio((X+X) ) ,4) ) +transpose(transpose((X|X) ,-5) ,7) ) ,-7) ,7) ) ) +((transpose(((((X+transpose(X,4) ) +transpose((shuffle(X) +transpose(transpose(X,4) ,7) ) ,7) ) +transpose((transpose((X+X) ,4) +echo(X,4,6) ) ,7) ) +((shuffle(X) +shuffle(shuffle(step(X,12) ) ) ) |(X|transpose(transpose(X,-5) ,4) ) ) ) ,4) +transpose((transpose((((X+X) +transpose((X+X) ,4) ) +transpose((X+X) ,7) ) ,-7) |(step(X,12) +transpose(shuffle(transpose(transpose((X|(X+X) ) ,-5) ,-7) ) ,7) ) ) ,4) ) +transpose(((((X|(X+X) ) |step(arpeggio(transpose((X+transpose(X,7) ) ,-7) ) ,12) ) +transpose(step(((arpeggio(shuffle(X) ) +transpose((transpose(echo(X,4,6) ,-7) +((X+transpose(X,4) ) +transpose(X,7) ) ) ,4) ) +transpose(transpose(transpose(X,-7) ,-5) ,7) ) ,12) ,4) ) +transpose((((transpose(shuffle(X) ,-7) +transpose(transpose(X,-7) ,4) ) +transpose(arpeggio(arpeggio(X) ) ,7) ) +transpose((transpose(X,-5) +transpose((X|X) ,7) ) ,4) ) ,7) ) ,7) ) ) ) ) +transpose((((((shuffle((transpose(X,-5) +transpose(X,7) ) ) +transpose(((transpose(X,-5) +transpose(arpeggio(X) ,7) ) +(((X|transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ) |transpose(X,-5) ) +transpose(transpose(transpose(shuffle(X) ,-7) ,-7) ,7) ) ) ,4) ) +transpose((transpose(transpose(transpose((arpeggio(X) +transpose(X,7) ) ,-5) ,-5) ,4) +(((transpose(arpeggio(X) ,-7) +transpose(transpose(((((X+transpose(X,4) ) +transpose(X,7) ) +transpose((X+transpose(X,7) ) ,4) ) +transpose(X,7) ) ,4) ,12) ) +transpose(arpeggio(((X+transpose(echo(X,4,6) ,4) ) +transpose(transpose(X,-5) ,7) ) ) ,12) ) +arpeggio(transpose(transpose(X,-7) ,4) ) ) ) ,7) ) +transpose((transpose(transpose(echo(echo(transpose(X,-7) ,4,6) ,4,6) ,4) ,-7) +(shuffle(shuffle((transpose(X,4) +(X+X) ) ) ) +transpose(transpose((echo(transpose(X,-7) ,4,6) +X) ,4) ,7) ) ) ,7) ) +transpose(transpose(transpose((((transpose(X,-7) +transpose(transpose((X|X) ,-7) ,4) ) +transpose(transpose((X+X) ,4) ,7) ) +transpose((transpose(X,-5) +step(shuffle(X) ,12) ) ,12) ) ,-5) ,4) ,12) ) +transpose(shuffle(((transpose(((arpeggio(X) |(step(X,12) |X) ) +(transpose((X+transpose(X,12) ) ,-5) +transpose(step(X,12) ,4) ) ) ,4) +transpose(((((transpose((X+transpose((step(X,12) +(X+transpose(X,12) ) ) ,12) ) ,4) +transpose(transpose(((transpose(X,-7) |transpose(X,-7) ) +(transpose(X,-7) +transpose(transpose(X,-7) ,7) ) ) ,-7) ,4) ) +transpose(echo(arpeggio(X) ,4,6) ,7) ) +transpose((((X|((X+X) |X) ) +transpose((X+transpose(X,7) ) ,7) ) +transpose(((X|X) +(arpeggio(echo(X,4,6) ) |X) ) ,12) ) ,12) ) +transpose(((transpose(transpose(X,-7) ,4) +transpose(((transpose(X,-5) |arpeggio(X) ) +((X|X) |(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,-7) +transpose(transpose(X,4) ,12) ) ) ) ,12) ) +(((X+transpose(X,7) ) +echo(X,4,6) ) |((X+transpose(X,-5) ) +(arpeggio(X) |step((X+X) ,12) ) ) ) ) ,4) ) ,4) ) +transpose((transpose(step(shuffle(step(X,12) ) ,12) ,-5) +transpose(transpose(step(transpose(transpose((X+transpose((X+X) ,12) ) ,4) ,4) ,12) ,-7) ,-7) ) ,7) ) ) ,7) ) ,7) ) ,4) ) +transpose(shuffle(transpose(transpose(transpose(transpose(transpose(((echo(X,4,6) +transpose(X,7) ) |transpose(transpose(arpeggio(X) ,-7) ,-7) ) ,4) ,-7) ,-7) ,-7) ,-5) ) ,7) ) ,7) ) +transpose((arpeggio(step(transpose((((transpose(transpose(transpose((shuffle(X) +transpose((X+transpose(X,12) ) ,7) ) ,4) ,-5) ,4) +transpose(transpose((transpose(X,4) +(X|X) ) ,-5) ,12) ) +transpose((arpeggio(transpose((shuffle(transpose(X,4) ) +transpose(X,-7) ) ,-5) ) |(((arpeggio(X) +transpose(transpose(X,4) ,7) ) |transpose(echo(((X+transpose(X,4) ) +transpose(X,7) ) ,4,6) ,4) ) +echo((((transpose(X,-7) +transpose(X,7) ) |transpose(X,-5) ) +(((X+transpose(X,4) ) +transpose(X,7) ) +transpose(transpose(X,-5) ,12) ) ) ,4,6) ) ) ,4) ) +transpose(((transpose(transpose(X,-5) ,-5) +transpose(transpose(transpose(X,-7) ,-5) ,7) ) +transpose((transpose((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(transpose(X,-7) ,7) ) ,-7) +(transpose(X,4) +echo((X+transpose(X,7) ) ,4,6) ) ) ,7) ) ,7) ) ,-7) ,12) ) +transpose(transpose((transpose(transpose(transpose(((transpose((step(transpose(X,-5) ,12) +transpose(transpose(X,-5) ,12) ) ,4) +transpose((step(X,12) |shuffle((X+transpose(X,12) ) ) ) ,-5) ) |transpose(shuffle((step(((X+transpose(X,7) ) +echo(X,4,6) ) ,12) +(X+transpose(X,12) ) ) ) ,4) ) ,-7) ,4) ,4) +(((shuffle((((echo(X,4,6) +transpose((((X+transpose((X+transpose(X,12) ) ,12) ) +transpose(transpose(transpose(X,4) ,4) ,4) ) +transpose((transpose(X,-7) +transpose(step(X,12) ,12) ) ,7) ) ,12) ) +transpose(((transpose(transpose(transpose(X,-7) ,-7) ,-7) +(((X+(X+transpose(X,12) ) ) +transpose(transpose((X|X) ,-7) ,4) ) +transpose(transpose(X,4) ,7) ) ) +step(transpose(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ,-5) ,12) ) ,4) ) +transpose(shuffle((echo(echo(X,4,6) ,4,6) |step(echo(X,4,6) ,12) ) ) ,7) ) ) +transpose((((arpeggio(X) +transpose(step(transpose(X,4) ,12) ,12) ) |((arpeggio(X) +transpose(arpeggio(((transpose(X,-7) +transpose(transpose(X,4) ,4) ) +transpose(transpose(X,4) ,7) ) ) ,4) ) +transpose(shuffle(((echo(X,4,6) +transpose((X|X) ,4) ) +transpose(echo(X,4,6) ,7) ) ) ,7) ) ) +transpose(((((echo(X,4,6) +X) +transpose(X,-7) ) |((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(X,7) ) +(transpose((X+transpose(X,12) ) ,-5) +transpose(((X|X) +(X|X) ) ,7) ) ) ) +(transpose(transpose(arpeggio(((X+transpose(X,4) ) +transpose(X,7) ) ) ,-5) ,-7) |(transpose(X,-5) +transpose(X,-5) ) ) ) ,4) ) ,4) ) +transpose(transpose(echo(transpose(((transpose(X,4) +(transpose((X+X) ,-5) +transpose(echo((X+X) ,4,6) ,12) ) ) +transpose((X+(X|X) ) ,12) ) ,-7) ,4,6) ,-5) ,7) ) +shuffle((echo(((shuffle(((X+transpose(X,4) ) +transpose(X,7) ) ) +transpose((((X+transpose(X,4) ) +transpose((X+transpose(X,7) ) ,7) ) +transpose(shuffle((X|(X|X) ) ) ,7) ) ,4) ) +transpose(arpeggio(((X+transpose(X,4) ) +transpose(X,7) ) ) ,7) ) ,4,6) +(arpeggio((X+transpose((X+X) ,7) ) ) +transpose(transpose((transpose(X,4) |(X+transpose(X,12) ) ) ,4) ,-5) ) ) ) ) ) ,-5) ,7) ) ,7) ) +transpose(step(transpose(transpose(transpose(shuffle(transpose(transpose(shuffle((transpose(transpose(X,4) ,4) +(X+transpose((X+X) ,7) ) ) ) ,-7) ,4) ) ,-5) ,4) ,-7) ,12) ,12) )
random seed used was 219476744

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