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:
((transpose((((arpeggio(((transpose(transpose(step(X,12) ,4) ,-7) +transpose(((((X+X) +transpose(X,7) ) +transpose(shuffle(((X+transpose(X,4) ) +transpose(X,7) ) ) ,7) ) +echo(transpose(((X+transpose(X,12) ) +transpose(arpeggio(X) ,12) ) ,-7) ,4,6) ) ,12) ) |(transpose(transpose((step(X,12) +transpose((X+transpose(X,7) ) ,7) ) ,-7) ,-5) +transpose((transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) +shuffle(step(transpose(transpose(X,4) ,4) ,12) ) ) ,12) ) ) ) +transpose(transpose(transpose(shuffle(arpeggio(shuffle(step(step(X,12) ,12) ) ) ) ,-5) ,-7) ,-5) ) +transpose((transpose(transpose((((transpose(((transpose((X+X) ,4) +transpose((shuffle(X) |((X+transpose(X,4) ) +transpose(X,7) ) ) ,12) ) |transpose(((echo(X,4,6) +transpose(X,4) ) +transpose((X|X) ,7) ) ,4) ) ,4) +shuffle(transpose((X|echo(X,4,6) ) ,-7) ) ) +transpose(echo((shuffle(transpose(X,4) ) +transpose(((X+X) |((X+X) +transpose((X+X) ,12) ) ) ,7) ) ,4,6) ,4) ) +transpose(((((X+transpose(X,12) ) +transpose(arpeggio(X) ,7) ) +transpose((X|step(transpose(step(X,12) ,-7) ,12) ) ,4) ) +transpose(transpose((shuffle(X) |echo(X,4,6) ) ,4) ,7) ) ,7) ) ,-5) ,4) |arpeggio(transpose(transpose((transpose((X+transpose(X,7) ) ,-7) +transpose(transpose(echo((transpose(X,-5) +transpose(X,4) ) ,4,6) ,-5) ,7) ) ,4) ,-5) ) ) ,12) ) |transpose(transpose((transpose(((((echo(shuffle((X+transpose(X,12) ) ) ,4,6) +transpose(((((transpose(X,-5) |X) +transpose((X+transpose((X+transpose(X,7) ) ,12) ) ,12) ) +transpose(((X+X) +transpose(X,12) ) ,4) ) +transpose((X|((X+transpose(X,4) ) +transpose(X,7) ) ) ,7) ) ,12) ) |(transpose((X+transpose(X,7) ) ,4) +transpose((X+transpose(X,7) ) ,12) ) ) +transpose((echo(transpose((transpose(X,4) +transpose(X,-7) ) ,4) ,4,6) +transpose(((step((X+transpose(X,12) ) ,12) +(X+transpose(X,12) ) ) +transpose((((X+X) +transpose(X,4) ) |transpose(shuffle(X) ,4) ) ,7) ) ,-5) ) ,4) ) +transpose(transpose(arpeggio(transpose((transpose(X,4) +transpose(transpose(arpeggio(X) ,-5) ,12) ) ,-5) ) ,-5) ,7) ) ,-5) +transpose(((((transpose(X,4) |transpose(transpose(X,4) ,-7) ) +transpose(transpose((X+transpose(X,7) ) ,4) ,12) ) +transpose(transpose(transpose(arpeggio(arpeggio(arpeggio((X+transpose(X,7) ) ) ) ) ,-7) ,-5) ,12) ) |((step((X+transpose(transpose(X,4) ,7) ) ,12) +transpose(echo(transpose((shuffle(((X+transpose(X,4) ) +transpose(X,7) ) ) +transpose(X,-7) ) ,-7) ,4,6) ,7) ) +transpose(echo(transpose(transpose(((X+X) +X) ,-7) ,-5) ,4,6) ,7) ) ) ,7) ) ,-7) ,-7) ) ,-5) +transpose(transpose(transpose(((step(transpose(transpose((X+transpose(X,12) ) ,4) ,4) ,12) +transpose(transpose((transpose((X|X) ,-5) +transpose(X,-5) ) ,4) ,4) ) +transpose(transpose(shuffle((transpose(X,4) +step(X,12) ) ) ,-7) ,7) ) ,-7) ,-7) ,12) ) +((echo(transpose(((transpose(transpose(transpose(transpose(X,-5) ,4) ,4) ,-5) +transpose(arpeggio((transpose(echo(step(X,12) ,4,6) ,-5) +arpeggio(transpose(arpeggio(X) ,4) ) ) ) ,-5) ) |transpose((shuffle(echo(step(echo(transpose(X,4) ,4,6) ,12) ,4,6) ) +transpose(((step((((transpose(transpose((X|X) ,4) ,4) |(step((X+transpose(X,12) ) ,12) |echo(X,4,6) ) ) +transpose((((transpose(X,4) +X) |(shuffle(X) |((X+transpose(X,4) ) +transpose(X,7) ) ) ) +(transpose(X,-5) +transpose(X,-7) ) ) ,4) ) +transpose(transpose(transpose(step(X,12) ,-7) ,4) ,7) ) ,12) +transpose((((transpose(step((X+transpose(X,7) ) ,12) ,4) +transpose((echo(X,4,6) |X) ,-5) ) +transpose(echo(transpose(transpose(X,-7) ,4) ,4,6) ,12) ) +transpose((echo((step((X+X) ,12) |((X+transpose(transpose(X,-7) ,4) ) +transpose(transpose(X,4) ,7) ) ) ,4,6) +echo(((transpose((X+X) ,-5) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ) +transpose(X,7) ) ,4,6) ) ,12) ) ,12) ) +transpose(transpose((((echo(transpose(X,4) ,4,6) +transpose((echo(X,4,6) +transpose(transpose(X,-5) ,12) ) ,4) ) +transpose(transpose(X,4) ,7) ) |(echo(X,4,6) +transpose((transpose(X,-7) +transpose(X,-5) ) ,12) ) ) ,4) ,-5) ) ,12) ) ,-7) ) ,-5) ,4,6) +transpose(step(transpose(transpose(((transpose(transpose(transpose(((step(transpose(echo(echo(X,4,6) ,4,6) ,4) ,12) +transpose(((echo((X+transpose(X,12) ) ,4,6) +transpose(X,4) ) +transpose(shuffle(X) ,7) ) ,12) ) |transpose(((shuffle((X+X) ) +transpose((transpose(X,4) +transpose((X+X) ,-5) ) ,4) ) +transpose(shuffle(((X+transpose(X,4) ) +transpose(X,7) ) ) ,7) ) ,-7) ) ,4) ,-7) ,-5) |(((transpose(shuffle(step(X,12) ) ,-7) +transpose(transpose(((X+transpose(shuffle(X) ,-5) ) +transpose(transpose(echo(X,4,6) ,-5) ,12) ) ,4) ,-5) ) +transpose(((arpeggio((transpose(transpose(arpeggio(arpeggio(transpose(X,-7) ) ) ,-5) ,-5) +transpose((step(transpose(X,-5) ,12) +transpose((transpose(echo(X,4,6) ,-5) +transpose(((((X+X) +(X+X) ) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ) +transpose((X+transpose(transpose(X,-5) ,12) ) ,7) ) ,7) ) ,12) ) ,12) ) ) +transpose(transpose((transpose((transpose(X,-7) +transpose((X+X) ,7) ) ,4) |(((transpose(X,-5) +transpose((X+transpose(X,7) ) ,4) ) +transpose((X|X) ,7) ) |(shuffle((X|X) ) |((X+X) +transpose((X+X) ,-7) ) ) ) ) ,-5) ,4) ) +transpose((arpeggio(X) +(echo((X+X) ,4,6) |step(X,12) ) ) ,7) ) ,4) ) +transpose((transpose((transpose((X|(X+transpose(X,7) ) ) ,-7) |shuffle((X+transpose(X,7) ) ) ) ,-7) +transpose((transpose(transpose(transpose(transpose(transpose(transpose(X,4) ,4) ,-7) ,-7) ,-5) ,-5) +transpose(transpose(transpose(transpose(shuffle(X) ,-5) ,-5) ,-5) ,12) ) ,12) ) ,7) ) ) +transpose(shuffle((echo(transpose(transpose((arpeggio((X+transpose(X,12) ) ) +transpose((X+X) ,-5) ) ,-7) ,-7) ,4,6) |(transpose(transpose((transpose(X,-5) +(transpose(X,-5) |((X+transpose(X,12) ) +(X+X) ) ) ) ,4) ,4) +transpose(transpose(echo((((X+transpose(X,4) ) +((X+transpose(X,4) ) +transpose(X,7) ) ) +transpose(transpose(arpeggio(X) ,-7) ,7) ) ,4,6) ,4) ,4) ) ) ) ,12) ) ,-7) ,-5) ,12) ,4) ) +transpose(transpose(((((transpose(arpeggio((arpeggio(((X+transpose(X,12) ) +((X+transpose(transpose(X,-7) ,4) ) +transpose((X+transpose(X,7) ) ,7) ) ) ) +((X+((shuffle(X) +transpose(X,4) ) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,7) ) ) |transpose((((X+transpose(X,7) ) +transpose((X+transpose(X,12) ) ,7) ) +(X|transpose(X,-5) ) ) ,4) ) ) ) ,-5) +transpose((((X+transpose(X,7) ) |(((X|X) +transpose((X+transpose(transpose(X,4) ,12) ) ,4) ) +transpose(((X|X) |X) ,7) ) ) +((transpose((X+(X+transpose(echo(X,4,6) ,12) ) ) ,4) +transpose(((((X+X) |transpose(X,-7) ) |((transpose(X,4) +transpose((X|X) ,4) ) +transpose((X+(X|X) ) ,7) ) ) +((((X+transpose(X,7) ) +transpose(transpose(X,-7) ,7) ) +transpose((transpose(X,-7) +X) ,4) ) +transpose((((X+transpose(X,4) ) +transpose(X,7) ) +X) ,7) ) ) ,4) ) +transpose(((shuffle(X) +transpose(step(transpose(X,-5) ,12) ,7) ) +(transpose(X,4) +X) ) ,7) ) ) ,4) ) +transpose(arpeggio(transpose(shuffle(shuffle(((step(X,12) +transpose(X,4) ) +transpose(step(X,12) ,7) ) ) ) ,4) ) ,7) ) |(transpose((((X|transpose(X,-7) ) +transpose(transpose(X,-7) ,4) ) +transpose(X,7) ) ,-5) +(echo(transpose(((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(transpose(X,-5) ,12) ) +transpose(transpose(step(X,12) ,-5) ,12) ) ,-7) ,4,6) +transpose(((X+transpose(X,7) ) +transpose(step(X,12) ,7) ) ,-5) ) ) ) +transpose(((((((echo(transpose(transpose(X,4) ,4) ,4,6) +arpeggio((X+transpose(X,7) ) ) ) +transpose((transpose((((X|X) |transpose(echo(X,4,6) ,4) ) +transpose(transpose((X|(X+transpose(X,12) ) ) ,4) ,7) ) ,4) +transpose(step(arpeggio((step((X+transpose(X,7) ) ,12) +X) ) ,12) ,7) ) ,4) ) +transpose(((arpeggio(((echo(transpose(echo((X|X) ,4,6) ,-7) ,4,6) +transpose((X|(X+X) ) ,4) ) +transpose((step(transpose(transpose(X,-5) ,4) ,12) +((((transpose(X,-7) +transpose(X,4) ) +transpose(X,7) ) +transpose(transpose(X,-5) ,4) ) +transpose(transpose(transpose(X,4) ,-5) ,7) ) ) ,7) ) ) +transpose((((transpose(((transpose(X,-5) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ) +transpose(transpose(X,4) ,7) ) ,4) +shuffle(((X+X) +transpose(X,-7) ) ) ) +transpose(transpose(((X+transpose(transpose(X,4) ,7) ) +transpose(transpose(X,4) ,12) ) ,-5) ,12) ) +(transpose((X+transpose(X,7) ) ,-5) |echo(transpose(transpose(X,4) ,-7) ,4,6) ) ) ,4) ) +transpose(((shuffle(((X+transpose(X,7) ) +transpose(X,12) ) ) +transpose(transpose((echo(X,4,6) |(X|X) ) ,4) ,7) ) +transpose(((step(X,12) +(arpeggio(step(X,12) ) |transpose(X,4) ) ) +transpose(arpeggio(X) ,-5) ) ,12) ) ,7) ) ,7) ) +transpose(echo(transpose(echo((step(step(echo((X+transpose(X,12) ) ,4,6) ,12) ,12) |(((X+transpose(echo(X,4,6) ,7) ) +transpose(shuffle((X|X) ) ,7) ) +transpose(transpose(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,-7) ,-5) ,-5) ) ) ,4,6) ,4) ,4,6) ,7) ) +transpose((transpose((arpeggio(transpose(echo(transpose((shuffle(transpose(X,-5) ) +transpose(X,12) ) ,-5) ,4,6) ,4) ) +(echo(((transpose(transpose(echo(X,4,6) ,-7) ,-5) +transpose((transpose(transpose(X,4) ,-5) |X) ,4) ) +transpose(transpose(step(echo(X,4,6) ,12) ,-7) ,7) ) ,4,6) |transpose(transpose((step(X,12) |((X|X) +transpose(step(X,12) ,7) ) ) ,-7) ,4) ) ) ,-5) +transpose((shuffle(transpose(((transpose(transpose(echo(((X+transpose(X,4) ) +transpose(X,7) ) ,4,6) ,-5) ,-7) +transpose(((X+transpose(step(X,12) ,12) ) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,7) ) ,12) ) |transpose(step(((X+X) +transpose(X,4) ) ,12) ,4) ) ,-5) ) |step(transpose((transpose(((echo(((X+transpose(X,7) ) +transpose(X,-5) ) ,4,6) |(shuffle((X+X) ) +transpose(((X+transpose(X,12) ) +step(X,12) ) ,12) ) ) +transpose(((((step(X,12) +transpose(X,7) ) +transpose((X|X) ,12) ) +transpose((((transpose(transpose(X,-7) ,-5) +shuffle(transpose(X,4) ) ) +transpose(transpose(transpose(X,4) ,-7) ,4) ) +transpose(transpose(step(X,12) ,4) ,7) ) ,4) ) +transpose(arpeggio(arpeggio(((X+transpose(X,4) ) +transpose(X,7) ) ) ) ,7) ) ,12) ) ,-7) |transpose((transpose(transpose(step(X,12) ,4) ,-5) +transpose(transpose(shuffle(arpeggio(X) ) ,-7) ,12) ) ,-5) ) ,-5) ,12) ) ,7) ) ,4) ) +transpose(((echo(transpose((X|step(X,12) ) ,-7) ,4,6) +transpose(((transpose(X,4) +transpose((X+transpose(X,7) ) ,7) ) +transpose((transpose(X,-7) +transpose(transpose(X,-7) ,7) ) ,-5) ) ,12) ) +echo(((shuffle(((((transpose((X+transpose(X,12) ) ,4) +transpose(X,4) ) +transpose(arpeggio(X) ,7) ) |transpose((((((X|X) +transpose(X,4) ) +transpose(transpose(X,-7) ,7) ) |transpose(X,-5) ) +transpose(echo((arpeggio(X) |transpose(X,-5) ) ,4,6) ,12) ) ,4) ) +transpose((((((step(echo(X,4,6) ,12) +transpose(((X+X) +(X+X) ) ,12) ) +transpose(transpose(X,-7) ,4) ) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,7) ) +transpose(transpose(transpose(X,-7) ,4) ,7) ) |transpose((arpeggio(X) |transpose(X,-7) ) ,-7) ) ,7) ) ) +transpose(shuffle(step((transpose(X,4) +transpose((X|echo(X,4,6) ) ,7) ) ,12) ) ,-5) ) |((((transpose(transpose(X,-7) ,-7) +transpose((transpose(X,4) +transpose((((X+transpose(echo(X,4,6) ,12) ) |transpose(X,4) ) |transpose((X+transpose(X,12) ) ,-7) ) ,12) ) ,4) ) +transpose(((((shuffle(X) +transpose(transpose(X,-5) ,7) ) +transpose(shuffle(X) ,4) ) +transpose(transpose((X+transpose(X,12) ) ,-7) ,7) ) +transpose(((X|transpose(X,-7) ) +transpose(X,12) ) ,7) ) ,7) ) +transpose(step(transpose((((transpose(X,-7) +transpose(transpose(X,-5) ,4) ) +transpose((((arpeggio(X) +transpose((X+X) ,12) ) +transpose((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(echo(X,4,6) ,7) ) ,12) ) +transpose(((X+transpose(X,12) ) +(X+transpose(X,7) ) ) ,-5) ) ,4) ) +transpose(transpose(echo((((X+transpose((X|X) ,4) ) +transpose(X,7) ) +step(X,12) ) ,4,6) ,4) ,7) ) ,-7) ,12) ,7) ) +(transpose(((arpeggio((X|X) ) +((echo(X,4,6) +transpose(transpose(X,-7) ,4) ) +transpose(X,7) ) ) |(echo(echo(transpose(X,-7) ,4,6) ,4,6) +transpose(transpose((transpose(X,-7) +transpose(transpose(X,4) ,7) ) ,-5) ,12) ) ) ,4) +transpose(((transpose(step(echo(X,4,6) ,12) ,-5) +transpose(transpose((X+transpose(X,7) ) ,-5) ,12) ) +transpose((((X+X) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,7) ) |transpose(transpose(arpeggio((X+transpose(X,12) ) ) ,4) ,4) ) ,7) ) ,-7) ) ) ) ,4,6) ) ,7) ) ,12) ) ,-5) ,7) ) )
random seed used was 121582289

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