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 17 generations the expression "X" became this:
((((echo(((echo(step((echo(X,4,6) +transpose(transpose((((transpose(X,-5) +transpose(X,4) ) +transpose(X,7) ) +(echo(X,4,6) +X) ) ,4) ,12) ) ,12) ,4,6) +transpose(((transpose(((X|step((X|X) ,12) ) |transpose(((X+transpose(X,4) ) +transpose(transpose(X,-5) ,7) ) ,4) ) ,4) +transpose((((transpose((transpose(transpose(X,-7) ,-7) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ) ,-7) +transpose(transpose(((X+X) |(X+X) ) ,-7) ,12) ) +transpose((transpose(transpose(shuffle(X) ,4) ,-7) +X) ,12) ) |transpose(shuffle(transpose(X,4) ) ,-5) ) ,4) ) +transpose(((transpose(arpeggio((transpose(X,-5) +transpose(transpose(X,4) ,7) ) ) ,-5) +transpose((echo(shuffle((X|X) ) ,4,6) +transpose(shuffle((X+transpose(transpose(X,4) ,7) ) ) ,7) ) ,4) ) +transpose(((step(arpeggio(X) ,12) +transpose(X,4) ) +transpose(echo(transpose(X,-7) ,4,6) ,7) ) ,7) ) ,7) ) ,7) ) +((transpose((transpose(shuffle(X) ,4) +transpose((X+transpose(X,-7) ) ,7) ) ,-7) |transpose(((X|X) +shuffle(X) ) ,-5) ) +transpose(transpose(transpose(arpeggio(transpose(X,4) ) ,4) ,-7) ,7) ) ) ,4,6) +transpose(((transpose(step(transpose(shuffle(transpose((X+transpose(X,12) ) ,-5) ) ,4) ,12) ,-5) +transpose((transpose(shuffle(shuffle((X+transpose(X,12) ) ) ) ,-5) |echo((transpose((X|step(echo(X,4,6) ,12) ) ,4) +((X+X) +transpose(transpose(X,4) ,7) ) ) ,4,6) ) ,-5) ) +transpose(echo(transpose(((arpeggio(shuffle((X+(X+transpose(X,12) ) ) ) ) |(echo(transpose((((X+transpose(X,12) ) +transpose(echo((X+transpose(X,7) ) ,4,6) ,4) ) +transpose(transpose(X,4) ,7) ) ,4) ,4,6) +transpose((X+transpose(transpose(X,-7) ,7) ) ,-7) ) ) |transpose(transpose(transpose((((transpose(transpose(X,-5) ,4) +transpose((echo(step(X,12) ,4,6) +transpose(X,-7) ) ,4) ) +transpose((((arpeggio(X) +transpose(echo(X,4,6) ,12) ) +transpose(transpose(X,4) ,4) ) +transpose((X+transpose(X,12) ) ,7) ) ,7) ) |transpose(arpeggio(X) ,-5) ) ,-5) ,4) ,-5) ) ,4) ,4,6) ,7) ) ,4) ) +transpose(transpose(((step(((((((X+transpose(X,4) ) +transpose(X,7) ) |transpose(X,-7) ) +transpose(X,-7) ) |(step(X,12) +transpose((X+transpose((X+X) ,12) ) ,12) ) ) +transpose(((transpose((step(transpose(X,-7) ,12) |(arpeggio(transpose(X,-5) ) +transpose((X|X) ,7) ) ) ,-5) +transpose((echo(transpose(X,4) ,4,6) +transpose((transpose(X,-7) |transpose(X,4) ) ,12) ) ,7) ) |((X+X) +transpose((X+transpose(transpose(transpose(X,-5) ,-7) ,12) ) ,7) ) ) ,7) ) ,12) +transpose(transpose(((X+transpose(((X|X) +transpose(transpose(X,-5) ,7) ) ,12) ) |transpose(X,-7) ) ,4) ,4) ) +transpose(step((transpose(shuffle(transpose(transpose(X,-5) ,4) ) ,-7) +arpeggio(((transpose(transpose(transpose(transpose(transpose(X,4) ,4) ,4) ,4) ,-5) +arpeggio(transpose(step(X,12) ,4) ) ) +shuffle(transpose(transpose(transpose((X+X) ,-5) ,-5) ,4) ) ) ) ) ,12) ,7) ) ,4) ,7) ) |step(((transpose(((transpose((step(echo(shuffle((X+X) ) ,4,6) ,12) +transpose(((((X+X) +transpose(transpose(X,-7) ,7) ) +transpose(step(transpose(X,-5) ,12) ,4) ) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,7) ) ,12) ) ,-7) +transpose(transpose(transpose(arpeggio((X+transpose(X,7) ) ) ,-7) ,-5) ,4) ) +transpose(transpose(transpose(shuffle((X|X) ) ,-7) ,4) ,7) ) ,4) +transpose(((step(echo((transpose((X|X) ,4) |((X|X) +X) ) ,4,6) ,12) +(arpeggio(transpose(X,4) ) +transpose((step(X,12) +X) ,12) ) ) +transpose(((transpose(((transpose(((shuffle(transpose(X,-5) ) +transpose((X+transpose(X,7) ) ,4) ) +transpose((transpose(X,-5) +X) ,7) ) ,4) +transpose(transpose(step(X,12) ,-7) ,4) ) +transpose(transpose(transpose((X+X) ,4) ,4) ,7) ) ,4) +transpose((((X+transpose(X,4) ) +transpose(X,7) ) |transpose(X,-7) ) ,4) ) +transpose((((((echo(X,4,6) +transpose((X|X) ,4) ) +transpose(((transpose(X,-5) +transpose(X,4) ) +transpose(transpose(X,-5) ,7) ) ,7) ) +transpose((transpose(X,4) |(X+X) ) ,4) ) +transpose((echo(echo(X,4,6) ,4,6) +transpose(X,12) ) ,7) ) +transpose(step(shuffle(X) ,12) ,7) ) ,7) ) ,12) ) ,4) ) +transpose((((((X+transpose(X,12) ) +transpose(echo(X,4,6) ,4) ) +transpose(transpose(X,-7) ,7) ) |step(step(step(((X+transpose(X,7) ) +transpose(transpose(X,-5) ,12) ) ,12) ,12) ,12) ) |echo(transpose(arpeggio((((X+X) +transpose((X+transpose(X,12) ) ,4) ) +transpose(X,7) ) ) ,4) ,4,6) ) ,7) ) ,12) ) +transpose(((((((transpose(((((echo(X,4,6) |transpose((X+X) ,4) ) +echo(transpose(shuffle((echo(X,4,6) |transpose(X,-5) ) ) ,-5) ,4,6) ) +transpose((echo((transpose((X+X) ,-7) |arpeggio(transpose(X,4) ) ) ,4,6) +transpose((transpose(transpose(((transpose(X,4) +(X+X) ) +transpose((X|X) ,7) ) ,-7) ,-5) |X) ,7) ) ,4) ) +transpose(transpose(transpose(shuffle(((step(X,12) +transpose(transpose(step(X,12) ,-5) ,4) ) +transpose(transpose(X,4) ,7) ) ) ,4) ,-7) ,7) ) ,4) +transpose(step(transpose(shuffle(echo((X+X) ,4,6) ) ,-5) ,12) ,4) ) |transpose((((transpose(arpeggio(X) ,4) +step(transpose(X,-5) ,12) ) |(X+X) ) +transpose(((step((X|X) ,12) +(transpose((X+transpose(X,7) ) ,4) +transpose(transpose(transpose((X|X) ,4) ,-5) ,12) ) ) +transpose((transpose(X,-7) |(X+transpose(X,7) ) ) ,12) ) ,12) ) ,4) ) +transpose(((transpose((((transpose(step(transpose(shuffle((shuffle((X+transpose(X,12) ) ) +(((X+transpose(X,4) ) +transpose(X,7) ) +transpose((X+X) ,7) ) ) ) ,-5) ,12) ,-7) +transpose(arpeggio(((X|transpose(transpose(X,4) ,4) ) +transpose(transpose(echo(X,4,6) ,-7) ,-7) ) ) ,4) ) +transpose(transpose((transpose(step(X,12) ,-7) +arpeggio(step(((shuffle(X) +transpose((X+transpose(X,12) ) ,4) ) +transpose(transpose(X,4) ,7) ) ,12) ) ) ,4) ,7) ) |shuffle((((X|X) +transpose(step(X,12) ,7) ) +transpose(shuffle((X|X) ) ,12) ) ) ) ,4) +transpose(transpose(((transpose((transpose(X,-5) +X) ,-5) +(X+transpose((X|X) ,7) ) ) |shuffle((echo(arpeggio((X+transpose(X,12) ) ) ,4,6) +((transpose(X,-7) +transpose(step(X,12) ,12) ) +(transpose((shuffle(X) |transpose(X,-7) ) ,-7) +transpose(transpose(X,-5) ,4) ) ) ) ) ) ,-7) ,12) ) +transpose((echo((transpose(((transpose(shuffle((X+transpose(X,12) ) ) ,-5) +transpose(transpose(X,-5) ,4) ) +(((transpose(X,-7) +transpose(transpose(X,-5) ,4) ) +transpose((transpose(X,4) |arpeggio(X) ) ,7) ) +transpose(((transpose(X,-5) +transpose(((X+transpose(X,12) ) +X) ,4) ) +transpose(transpose(X,-5) ,7) ) ,7) ) ) ,-5) +echo(((shuffle(shuffle((X|(X+transpose(X,7) ) ) ) ) +transpose(transpose(shuffle(transpose(X,-5) ) ,4) ,4) ) +transpose(((X+transpose(X,7) ) +transpose((X+transpose(X,12) ) ,12) ) ,7) ) ,4,6) ) ,4,6) +(transpose(((arpeggio(transpose(X,-5) ) +transpose((X+transpose(transpose(X,4) ,7) ) ,4) ) +transpose(echo(((((X+X) +transpose(X,7) ) +transpose((((X+transpose(X,4) ) +transpose(X,7) ) +X) ,4) ) +transpose(arpeggio(transpose(X,4) ) ,7) ) ,4,6) ,7) ) ,4) +transpose(echo(step(transpose(((((X+X) +(X+transpose(step(X,12) ,7) ) ) +transpose(arpeggio((X+transpose(X,12) ) ) ,12) ) +transpose(transpose(((X+X) +transpose(X,-5) ) ,-7) ,12) ) ,4) ,12) ,4,6) ,7) ) ) ,12) ) ,4) ) +transpose((((((((shuffle(((transpose(X,-5) +X) |transpose(transpose(X,4) ,4) ) ) +transpose(step(transpose(transpose(transpose(X,-5) ,-5) ,-7) ,12) ,4) ) +transpose(((transpose(transpose(X,4) ,-7) +shuffle(X) ) +transpose(step((X+transpose(X,12) ) ,12) ,4) ) ,7) ) +transpose(echo(echo(transpose(transpose((X|transpose(X,4) ) ,-7) ,-7) ,4,6) ,4,6) ,7) ) +transpose(echo(transpose(((transpose(transpose(X,-7) ,4) +transpose((X|X) ,7) ) +step((X|((X+transpose(X,4) ) +transpose(X,7) ) ) ,12) ) ,-5) ,4,6) ,7) ) +transpose(transpose(echo(((((transpose(step(step(X,12) ,12) ,4) +transpose(step(transpose(X,-5) ,12) ,7) ) +transpose(((echo((X|X) ,4,6) |(X+((X+transpose(X,4) ) +transpose(X,7) ) ) ) +transpose((transpose(step(X,12) ,-5) +transpose((X+transpose(arpeggio(X) ,-7) ) ,12) ) ,7) ) ,7) ) +transpose((transpose(step(arpeggio(((X|X) +transpose(shuffle(X) ,12) ) ) ,12) ,4) +shuffle((echo(shuffle(X) ,4,6) |arpeggio(transpose((X|X) ,4) ) ) ) ) ,4) ) +transpose(((echo((((X+transpose(X,7) ) +transpose(X,4) ) +transpose(transpose(X,-5) ,7) ) ,4,6) +(transpose(X,4) +transpose(transpose(transpose(X,4) ,-7) ,7) ) ) +transpose(transpose((transpose((X+transpose(X,7) ) ,-7) +transpose(transpose(X,4) ,12) ) ,4) ,7) ) ,7) ) ,4,6) ,-5) ,12) ) +transpose((transpose((transpose(arpeggio(((((transpose(X,4) |transpose((X+transpose(X,12) ) ,-5) ) +step((X|X) ,12) ) +transpose((X+transpose(X,-5) ) ,12) ) |transpose(echo(((echo(X,4,6) +((X+transpose(X,4) ) +transpose(X,7) ) ) +(transpose(X,4) +transpose(X,12) ) ) ,4,6) ,-7) ) ) ,4) |transpose((echo(transpose(X,4) ,4,6) |X) ,-5) ) ,-5) +transpose((transpose(shuffle(((X+transpose(X,7) ) +transpose(transpose((X+step(X,12) ) ,-5) ,7) ) ) ,-7) +transpose((transpose(arpeggio(echo((X+transpose(X,12) ) ,4,6) ) ,4) +transpose(step((transpose(X,4) |X) ,12) ,4) ) ,12) ) ,12) ) ,4) ) +transpose(transpose(shuffle(transpose((X+transpose(X,12) ) ,-7) ) ,4) ,7) ) ,7) ) +arpeggio(shuffle(transpose(arpeggio(((transpose(transpose(echo(X,4,6) ,-7) ,4) +((X+transpose(((X+transpose((X+transpose(X,12) ) ,4) ) +transpose(X,7) ) ,7) ) |(((echo(shuffle(transpose(transpose(X,4) ,-7) ) ,4,6) +transpose(step(transpose(echo(X,4,6) ,-7) ,12) ,7) ) +transpose(((((((X+transpose(X,7) ) +transpose(echo(X,4,6) ,4) ) +transpose(X,7) ) +((X|X) +transpose(X,7) ) ) +transpose(((((X+transpose(X,4) ) +transpose(X,7) ) +transpose((echo(X,4,6) |(X+X) ) ,4) ) +transpose(transpose(transpose(X,4) ,-5) ,7) ) ,7) ) |((X+X) +X) ) ,4) ) +transpose(transpose((transpose((X+X) ,-7) +transpose(transpose(X,-5) ,12) ) ,4) ,7) ) ) ) +transpose(transpose((transpose(arpeggio(step(step(X,12) ,12) ) ,-5) +transpose(transpose(echo(transpose((X|X) ,-7) ,4,6) ,-5) ,-7) ) ,-7) ,12) ) ) ,-5) ) ) ) +transpose((transpose(((((transpose(arpeggio(step((transpose(X,-7) +X) ,12) ) ,-5) +transpose((step(transpose(shuffle(transpose((X|X) ,4) ) ,-5) ,12) +transpose(transpose(((transpose(arpeggio((transpose((X+transpose(X,7) ) ,-7) |shuffle((X+transpose(X,12) ) ) ) ) ,4) +transpose(((X+transpose((X+X) ,7) ) +transpose(arpeggio(echo(X,4,6) ) ,12) ) ,4) ) +transpose(transpose(((((X+transpose(X,4) ) +transpose(X,7) ) +transpose((X+transpose(transpose(echo(X,4,6) ,4) ,12) ) ,12) ) +transpose(transpose((transpose(X,4) |arpeggio(transpose(X,4) ) ) ,-5) ,12) ) ,-7) ,7) ) ,-5) ,12) ) ,12) ) +transpose((step((((transpose((X+transpose((X+X) ,12) ) ,4) +shuffle((X|transpose((X+X) ,-5) ) ) ) |arpeggio(((transpose(transpose(transpose(X,-5) ,4) ,-5) +transpose(echo(((X+X) +transpose(X,-5) ) ,4,6) ,4) ) +transpose(step(shuffle(transpose(X,-5) ) ,12) ,7) ) ) ) +transpose((step(transpose(X,-7) ,12) |shuffle(arpeggio((X+arpeggio(X) ) ) ) ) ,7) ) ,12) |step(step(transpose((((X|transpose(X,-7) ) +transpose(X,12) ) |((echo(arpeggio(X) ,4,6) +transpose(shuffle(X) ,4) ) +transpose(echo(X,4,6) ,7) ) ) ,-5) ,12) ,12) ) ,4) ) +transpose(transpose((arpeggio(transpose((X+transpose(transpose(X,-7) ,12) ) ,-5) ) +((step(echo((transpose(X,-5) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ) ,4,6) ,12) +transpose(step(arpeggio(transpose(transpose(X,-5) ,4) ) ,12) ,7) ) +transpose(transpose(transpose(((X+(X+transpose(X,12) ) ) |transpose(X,4) ) ,4) ,4) ,12) ) ) ,-7) ,7) ) |(echo(((step(((X+transpose(X,12) ) |transpose(X,-7) ) ,12) +transpose((((X+transpose(X,12) ) |X) +transpose((X|X) ,12) ) ,7) ) +((((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ) +transpose(transpose(transpose(transpose(X,4) ,-7) ,4) ,4) ) +transpose(((X|X) +transpose(X,12) ) ,7) ) |(((echo(X,4,6) +transpose((X+X) ,7) ) +transpose((X+transpose((transpose(X,-7) |shuffle(X) ) ,7) ) ,4) ) +transpose(step(X,12) ,7) ) ) ) ,4,6) +transpose(arpeggio(transpose(echo(shuffle((((X+transpose(X,-7) ) +(X+transpose(arpeggio(X) ,7) ) ) +transpose(transpose(X,-5) ,4) ) ) ,4,6) ,-7) ) ,12) ) ) ,4) |transpose(arpeggio(step(transpose(((transpose((X|X) ,-7) +transpose((X+X) ,7) ) +transpose(((transpose(X,4) +transpose(echo(X,4,6) ,12) ) +(X+transpose(X,7) ) ) ,12) ) ,-5) ,12) ) ,-7) ) ,7) ) ,12) )
random seed used was 149405715

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