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 19 generations the expression "X" became this:
(transpose(((echo(transpose((echo(((step(echo(shuffle(step(echo(X,4,6) ,12) ) ,4,6) ,12) +transpose(shuffle(transpose((step((step(X,12) |transpose(X,-5) ) ,12) +transpose((X+transpose(echo(echo(X,4,6) ,4,6) ,7) ) ,7) ) ,-7) ) ,4) ) +transpose(arpeggio(echo(step(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ,4,6) ) ,7) ) ,4,6) +(((step(shuffle(X) ,12) +transpose(((X+transpose(shuffle(X) ,4) ) +transpose(arpeggio(X) ,7) ) ,7) ) |(echo(((transpose((X+X) ,4) |transpose(X,4) ) +transpose((((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(transpose(X,-7) ,4) ) +transpose(arpeggio(X) ,7) ) +((X+transpose(transpose(X,4) ,4) ) +transpose((X|X) ,7) ) ) ,12) ) ,4,6) +((X+transpose(transpose(step(X,12) ,-5) ,4) ) +transpose(echo((X+transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ) ,4,6) ,7) ) ) ) |echo((transpose(transpose((((((X+transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ) +transpose(X,7) ) |echo(arpeggio(X) ,4,6) ) +transpose((((X+transpose(step(X,12) ,12) ) +X) |(X|(transpose(X,-5) +transpose((X|X) ,7) ) ) ) ,4) ) +transpose(((X+X) |arpeggio(X) ) ,7) ) ,-5) ,4) +transpose(transpose(shuffle((X+transpose(((transpose(X,-7) +transpose(echo((X+transpose(X,12) ) ,4,6) ,4) ) +transpose(transpose(X,4) ,7) ) ,7) ) ) ,-7) ,7) ) ,4,6) ) ) ,-7) ,4,6) +transpose((((shuffle((transpose((X+X) ,-7) +transpose(step(X,12) ,12) ) ) +transpose(((echo(arpeggio(((X+transpose((X+transpose(X,12) ) ,4) ) +transpose(X,7) ) ) ,4,6) +transpose(echo(transpose(shuffle(shuffle(transpose(X,-7) ) ) ,4) ,4,6) ,4) ) +transpose(shuffle((shuffle(X) +transpose(echo(shuffle(step(X,12) ) ,4,6) ,12) ) ) ,7) ) ,-5) ) +((transpose(echo(arpeggio(arpeggio(X) ) ,4,6) ,-7) |echo(step(transpose(X,4) ,12) ,4,6) ) +transpose(((transpose(echo(((((((((((X|X) +transpose(transpose(X,4) ,4) ) +transpose(X,7) ) +transpose((((echo((X+transpose(X,7) ) ,4,6) +transpose(transpose((X+transpose(X,7) ) ,4) ,4) ) +transpose(arpeggio((X+transpose(X,12) ) ) ,7) ) +transpose(shuffle(X) ,7) ) ,7) ) +transpose((echo(X,4,6) +echo(X,4,6) ) ,12) ) +transpose(((echo(step(transpose(transpose(X,-7) ,-5) ,12) ,4,6) +transpose(((((X+transpose(X,7) ) +transpose(step(X,12) ,4) ) +transpose(transpose((X+transpose(transpose(X,-7) ,7) ) ,-5) ,7) ) +transpose(echo(shuffle(step(shuffle(X) ,12) ) ,4,6) ,7) ) ,4) ) +transpose(((transpose((X+X) ,4) +transpose(step(X,12) ,4) ) +transpose(X,7) ) ,7) ) ,4) ) +transpose(transpose(transpose(((echo(X,4,6) +transpose(shuffle(X) ,4) ) +transpose(X,7) ) ,-7) ,4) ,7) ) +transpose(arpeggio(((X|X) +transpose(((echo(((X+transpose(X,4) ) +transpose((X|X) ,7) ) ,4,6) +transpose(echo((X|X) ,4,6) ,4) ) +transpose(echo(X,4,6) ,7) ) ,7) ) ) ,4) ) +transpose(transpose((echo(arpeggio(X) ,4,6) +transpose((X+transpose(X,7) ) ,7) ) ,-5) ,7) ) +transpose((step((transpose((((X+transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ) +transpose(arpeggio(X) ,7) ) +transpose(step((X+transpose(echo(X,4,6) ,7) ) ,12) ,7) ) ,-7) +transpose(step(transpose(X,-7) ,12) ,7) ) ,12) +transpose((((shuffle(X) +transpose((X+transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,7) ) ,7) ) +echo(X,4,6) ) +transpose((X+X) ,7) ) ,4) ) ,12) ) ,4,6) ,4) +transpose(echo(transpose(transpose(((echo(X,4,6) +transpose(((X+transpose((X+transpose(shuffle(X) ,7) ) ,4) ) +transpose(X,7) ) ,4) ) +transpose(arpeggio(((arpeggio(X) +transpose(((X+transpose(X,12) ) +transpose(step(X,12) ,7) ) ,4) ) +transpose(arpeggio(transpose(X,-5) ) ,7) ) ) ,7) ) ,-5) ,4) ,4,6) ,4) ) +transpose((transpose((arpeggio(transpose(((shuffle((X+transpose(X,7) ) ) |arpeggio(step(X,12) ) ) +transpose((transpose(X,-7) +X) ,12) ) ,-5) ) +(arpeggio(shuffle(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,-5) ) ) +(echo(step(X,12) ,4,6) +transpose(step(X,12) ,7) ) ) ) ,-7) +transpose((transpose(step((((X+transpose(X,4) ) +transpose(X,7) ) +(((X|X) +transpose(((transpose(X,4) +transpose(arpeggio(X) ,12) ) |X) ,4) ) +transpose(arpeggio(X) ,7) ) ) ,12) ,4) +((transpose(((X+transpose(X,7) ) +transpose(step(transpose(X,4) ,12) ,12) ) ,-5) +transpose(shuffle(echo(echo(arpeggio(echo(transpose(X,4) ,4,6) ) ,4,6) ,4,6) ) ,12) ) |(step(X,12) |arpeggio(transpose(transpose(arpeggio(X) ,4) ,-5) ) ) ) ) ,7) ) ,7) ) ,12) ) ) +transpose((((transpose(step(arpeggio((echo(X,4,6) +transpose(step(step(X,12) ,12) ,7) ) ) ,12) ,-5) |step(shuffle((((((transpose(X,-5) |X) +transpose((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(X,7) ) ,7) ) +transpose(X,4) ) |echo((X|(X|transpose(X,4) ) ) ,4,6) ) |echo(echo(X,4,6) ,4,6) ) ) ,12) ) +transpose(echo(echo(((((arpeggio((((arpeggio(echo(X,4,6) ) +transpose((echo(X,4,6) +transpose(echo(X,4,6) ,7) ) ,7) ) +transpose((((step(X,12) |step(X,12) ) +transpose((echo(X,4,6) +((X+transpose(X,4) ) +transpose(X,7) ) ) ,4) ) +transpose(shuffle((X+X) ) ,7) ) ,4) ) +transpose(step(echo(X,4,6) ,12) ,7) ) ) +transpose(arpeggio(transpose(transpose(echo((X|X) ,4,6) ,-5) ,-7) ) ,4) ) +transpose(((transpose((((X+transpose(X,12) ) +transpose(X,4) ) +transpose(shuffle(X) ,7) ) ,-5) +transpose(echo(X,4,6) ,4) ) +transpose((shuffle(echo(X,4,6) ) +transpose(echo(shuffle(X) ,4,6) ,7) ) ,7) ) ,7) ) +transpose(shuffle(transpose((transpose(arpeggio(transpose(X,4) ) ,4) +transpose((echo(X,4,6) |((arpeggio(X) +transpose(step(X,12) ,4) ) +transpose(echo(X,4,6) ,7) ) ) ,7) ) ,-5) ) ,4) ) +transpose(step((((step(step(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ,12) +transpose((((X|X) +transpose(X,12) ) |step(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ) ,4) ) +transpose(shuffle(step(X,12) ) ,7) ) +transpose(transpose((X+transpose(X,12) ) ,-5) ,-7) ) ,12) ,7) ) ,4,6) ,4,6) ,4) ) +transpose(echo((((arpeggio(((transpose(X,4) +transpose(X,4) ) +transpose(shuffle(((X+transpose(X,4) ) +transpose(X,7) ) ) ,7) ) ) +transpose(echo(step((((step(X,12) +(X|X) ) |arpeggio(transpose(X,-5) ) ) +(((((X+X) +transpose(transpose(X,-7) ,4) ) +transpose(transpose(X,-7) ,7) ) +transpose(step(X,12) ,7) ) +transpose(((X+transpose(arpeggio(X) ,4) ) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,7) ) ,7) ) ) ,12) ,4,6) ,12) ) +transpose((transpose(echo((echo(X,4,6) +transpose(arpeggio(X) ,7) ) ,4,6) ,-5) +transpose(transpose(transpose(shuffle((X+X) ) ,-5) ,-7) ,7) ) ,7) ) +(((transpose(step((shuffle((echo(step(X,12) ,4,6) +transpose(X,12) ) ) |transpose(echo(X,4,6) ,4) ) ,12) ,4) +transpose(((transpose((transpose(X,-7) +transpose(transpose(echo(X,4,6) ,-5) ,7) ) ,-7) +transpose(arpeggio((echo((X|X) ,4,6) +transpose(arpeggio(X) ,12) ) ) ,4) ) +transpose(echo(((transpose(echo(X,4,6) ,-7) +transpose(arpeggio(X) ,4) ) +transpose(shuffle(X) ,7) ) ,4,6) ,7) ) ,7) ) +transpose((transpose(echo(((X+transpose(transpose(X,-7) ,7) ) +step(echo(X,4,6) ,12) ) ,4,6) ,4) |transpose(echo(transpose(arpeggio(X) ,-7) ,4,6) ,-7) ) ,4) ) +transpose(transpose(((transpose(echo(shuffle((arpeggio(X) +transpose((X+X) ,12) ) ) ,4,6) ,4) +transpose(((transpose(shuffle((X|X) ) ,-7) +(((X+transpose(step(X,12) ,4) ) +transpose((X+X) ,7) ) |(((X+transpose(X,4) ) +transpose(X,7) ) |(X+transpose(X,7) ) ) ) ) +transpose(step(arpeggio(shuffle(echo(X,4,6) ) ) ,12) ,7) ) ,4) ) +transpose(((arpeggio(transpose(X,-7) ) +transpose(step(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ,4) ) +transpose(transpose((echo(X,4,6) +transpose((X+transpose(X,7) ) ,7) ) ,4) ,7) ) ,7) ) ,4) ,7) ) ) ,4,6) ,7) ) ,12) ) ,4) ) +transpose((shuffle(((arpeggio(transpose(arpeggio(((step(X,12) +transpose(step(transpose(X,-7) ,12) ,4) ) +transpose(transpose(transpose(X,-7) ,-5) ,7) ) ) ,4) ) +transpose(step(echo(((transpose(((X+transpose(X,7) ) +X) ,-5) +transpose((step(transpose(transpose(X,4) ,-5) ,12) +transpose(transpose(step(X,12) ,-5) ,-5) ) ,7) ) +shuffle(arpeggio(arpeggio(X) ) ) ) ,4,6) ,12) ,4) ) +transpose(shuffle((((shuffle(echo(X,4,6) ) |echo(X,4,6) ) +transpose((((shuffle(shuffle(X) ) +transpose(transpose(arpeggio(X) ,-5) ,7) ) +transpose(echo((echo(X,4,6) +step(X,12) ) ,4,6) ,4) ) +transpose(transpose(X,4) ,7) ) ,4) ) +transpose(transpose((echo((X+X) ,4,6) |((echo(X,4,6) +transpose(shuffle(X) ,4) ) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,7) ) ) ,-7) ,7) ) ) ,7) ) ) +transpose(shuffle(((step(((shuffle(shuffle((transpose((X+transpose(X,7) ) ,-5) |echo(transpose((X+transpose(X,7) ) ,4) ,4,6) ) ) ) +transpose((arpeggio(step(transpose(X,-7) ,12) ) +transpose(echo(transpose(X,4) ,4,6) ,7) ) ,7) ) |echo(transpose(X,-7) ,4,6) ) ,12) +transpose(((arpeggio(echo(step(transpose(echo(X,4,6) ,-7) ,12) ,4,6) ) +transpose(((transpose((transpose(((X+transpose(X,7) ) +transpose(arpeggio(transpose(arpeggio(X) ,-5) ) ,7) ) ,-5) +transpose(shuffle(X) ,12) ) ,4) +transpose(((((((transpose(X,-5) +transpose(X,7) ) +transpose(step((X+transpose(X,12) ) ,12) ,4) ) +transpose((X+transpose(X,7) ) ,7) ) |(((step(arpeggio(arpeggio(X) ) ,12) +echo((X|shuffle(X) ) ,4,6) ) +transpose(shuffle((X+transpose(X,12) ) ) ,4) ) +transpose(shuffle(transpose((X+transpose(X,7) ) ,-7) ) ,7) ) ) +transpose(echo(echo((arpeggio((X+transpose(X,7) ) ) +transpose((X+transpose(echo(X,4,6) ,7) ) ,7) ) ,4,6) ,4,6) ,4) ) +transpose(arpeggio((((echo(X,4,6) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ) +transpose(echo(X,4,6) ,7) ) +transpose(transpose(echo((X+transpose(X,7) ) ,4,6) ,-5) ,12) ) ) ,7) ) ,12) ) +((transpose(step(((echo(step(transpose(X,4) ,12) ,4,6) +transpose(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ,4) ) +transpose(arpeggio(X) ,7) ) ,12) ,-7) +transpose((((((((X+transpose(shuffle(X) ,7) ) +arpeggio(X) ) +transpose(transpose(step(X,12) ,4) ,4) ) +transpose(shuffle(arpeggio(((X+transpose(X,4) ) +transpose(X,7) ) ) ) ,7) ) +(X+((X+transpose(X,4) ) +transpose(X,7) ) ) ) +transpose(((shuffle(transpose(X,-7) ) |X) +transpose(transpose(echo(shuffle(arpeggio(X) ) ,4,6) ,-7) ,12) ) ,7) ) +transpose(echo((arpeggio((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(step(X,12) ,12) ) ) +transpose(((transpose((((X+transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ) +transpose(transpose(X,-7) ,7) ) +transpose(echo((X+X) ,4,6) ,12) ) ,-7) +transpose(echo(shuffle(X) ,4,6) ,4) ) +transpose((transpose(X,4) +transpose(echo(((X+transpose(X,4) ) +transpose(X,7) ) ,4,6) ,12) ) ,7) ) ,7) ) ,4,6) ,7) ) ,7) ) +transpose(echo((((step((arpeggio(X) +transpose(transpose(X,-5) ,12) ) ,12) +transpose(arpeggio(((X+transpose(X,4) ) +transpose(X,7) ) ) ,7) ) +(X+transpose(shuffle(X) ,7) ) ) +transpose(shuffle(((shuffle(transpose(echo(X,4,6) ,-5) ) +transpose(step(shuffle(X) ,12) ,4) ) +transpose(transpose((X|((X+transpose(X,4) ) +transpose(X,7) ) ) ,-7) ,7) ) ) ,7) ) ,4,6) ,12) ) ) ,4) ) +transpose((shuffle(((((echo((transpose(echo(X,4,6) ,4) +transpose((echo(X,4,6) |step(X,12) ) ,7) ) ,4,6) +transpose(transpose(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,-7) ,4) ,4) ) +transpose(transpose(transpose((transpose(X,-5) +((X+transpose(X,-7) ) +X) ) ,4) ,-7) ,7) ) +transpose((echo(transpose(transpose(X,-5) ,-5) ,4,6) +transpose(transpose((echo((transpose(X,-7) |(X+transpose(X,12) ) ) ,4,6) +transpose(shuffle(X) ,12) ) ,-5) ,7) ) ,4) ) +transpose(transpose(echo(step(X,12) ,4,6) ,-7) ,7) ) ) +arpeggio(echo(arpeggio(echo(step(echo(transpose(step(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ,12) ,-7) ,4,6) ,12) ,4,6) ) ,4,6) ) ) ,7) ) ,4) ) +transpose(transpose((transpose((((arpeggio(((arpeggio(X) |X) +transpose(transpose(echo(X,4,6) ,-7) ,12) ) ) +transpose((transpose(shuffle(transpose(X,-7) ) ,-7) +transpose(transpose(transpose(step((step(X,12) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ) ,12) ,-7) ,-5) ,7) ) ,4) ) +transpose(echo((transpose(shuffle(X) ,-7) |X) ,4,6) ,7) ) |(((((X+X) +transpose((X|X) ,-7) ) +transpose((arpeggio(echo(echo(X,4,6) ,4,6) ) +transpose(shuffle(((X+transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ) +transpose(X,7) ) ) ,7) ) ,7) ) +transpose((arpeggio(transpose(step(X,12) ,-7) ) +shuffle(transpose(transpose(transpose(X,4) ,-7) ,4) ) ) ,4) ) +transpose(shuffle((shuffle((X|X) ) +transpose(echo((X+transpose(X,12) ) ,4,6) ,7) ) ) ,7) ) ) ,-5) +transpose(echo(shuffle(shuffle(echo((step(X,12) +transpose(X,12) ) ,4,6) ) ) ,4,6) ,7) ) ,-7) ,7) ) ) ,7) ) ,7) ) ,4) +transpose(arpeggio(transpose(transpose(step(arpeggio(step(transpose(echo(arpeggio(X) ,4,6) ,-7) ,12) ) ,12) ,-5) ,4) ) ,7) )
random seed used was 68118178

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