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

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