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:
Seed:
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After 16 generations the expression "X" became this:
transpose((step((((transpose(transpose(transpose(X,-7) ,4) ,-5) |shuffle(((((X+transpose((X+X) ,4) ) +transpose(shuffle(X) ,7) ) +transpose(shuffle(X) ,4) ) +transpose(echo(X,4,6) ,7) ) ) ) +transpose(transpose(step(X,12) ,-5) ,7) ) +transpose(shuffle(shuffle(((((transpose(X,4) +(shuffle(X) +transpose((X+X) ,7) ) ) +transpose(transpose(step(transpose(X,-5) ,12) ,4) ,7) ) +transpose(X,7) ) +transpose(transpose(transpose(transpose(((X+X) +transpose((X+transpose(X,7) ) ,7) ) ,-7) ,-5) ,-5) ,12) ) ) ) ,7) ) ,12) +transpose(echo((((((shuffle(X) +(transpose(X,-5) +transpose(((X+X) +transpose(X,4) ) ,12) ) ) |transpose(shuffle(transpose(X,-5) ) ,-5) ) +transpose((transpose((arpeggio(X) +transpose((X+X) ,7) ) ,-7) |transpose((transpose(echo(X,4,6) ,4) +transpose(((X|X) +transpose(X,4) ) ,12) ) ,4) ) ,-7) ) +transpose(((transpose(arpeggio(transpose(echo(X,4,6) ,4) ) ,-7) |transpose(shuffle((((echo(X,4,6) +transpose(X,4) ) +transpose(echo(X,4,6) ,7) ) +transpose(transpose((transpose(X,-7) +transpose(X,7) ) ,-7) ,12) ) ) ,4) ) +transpose(arpeggio(arpeggio(transpose((X|transpose(X,-7) ) ,4) ) ) ,12) ) ,4) ) +transpose(((transpose(((((X+transpose(X,4) ) +transpose(X,7) ) +transpose((X+X) ,12) ) |((step((X+X) ,12) +transpose(step((X+transpose(X,12) ) ,12) ,4) ) +transpose(transpose((X|X) ,-5) ,7) ) ) ,-7) +transpose(echo(((X+transpose(transpose(X,-7) ,7) ) +((transpose(X,4) +transpose(transpose(X,-7) ,4) ) +transpose(transpose(X,4) ,7) ) ) ,4,6) ,7) ) +((transpose((step(X,12) +(arpeggio(X) +transpose(transpose(X,4) ,12) ) ) ,4) +transpose(transpose(((((X+transpose(X,4) ) +transpose(X,7) ) +(X|X) ) +X) ,4) ,12) ) |transpose((((X|X) +X) +transpose((X+X) ,7) ) ,-5) ) ) ,7) ) ,4,6) ,12) ) ,4)
random seed used was 234792112 EXPR = arpeggio((step(transpose((shuffle(step(shuffle(echo(transpose((X|shuffle(X) ) ,4) ,4,6) ) ,12) ) +transpose(transpose(((step((arpeggio(X) +X) ,12) +transpose(((transpose((X+transpose(X,7) ) ,-7) +transpose(transpose(step(X,12) ,-7) ,4) ) +transpose(((echo(X,4,6) +transpose(X,4) ) +transpose(shuffle((X+X) ) ,12) ) ,7) ) ,7) ) +transpose((shuffle(((X+transpose(X,12) ) +transpose(X,12) ) ) +step(echo(transpose(shuffle(X) ,4) ,4,6) ,12) ) ,7) ) ,-7) ,7) ) ,4) ,12) +transpose(shuffle(((((transpose(arpeggio((((step(echo(X,4,6) ,12) +step(transpose(X,-7) ,12) ) |((transpose((X+X) ,-5) +transpose(transpose((X+transpose(X,7) ) ,-7) ,4) ) +transpose(transpose(transpose(X,-5) ,-7) ,7) ) ) +transpose(((transpose(X,-7) +transpose(((X+transpose(X,12) ) +transpose(X,12) ) ,12) ) +transpose(((X+X) +transpose(transpose(X,-7) ,7) ) ,7) ) ,12) ) ) ,-5) +transpose(transpose(echo(((arpeggio((((X+X) +(X|X) ) +(X+transpose(X,12) ) ) ) +transpose(arpeggio((X+transpose(((X+transpose(X,7) ) +transpose(transpose(X,4) ,12) ) ,12) ) ) ,4) ) +transpose(transpose(transpose((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(shuffle(X) ,7) ) ,-7) ,-7) ,7) ) ,4,6) ,-7) ,4) ) +transpose(step((transpose(((transpose(step(X,12) ,-5) +transpose(echo((shuffle(X) +transpose(X,12) ) ,4,6) ,4) ) +transpose(shuffle((X|X) ) ,7) ) ,4) |transpose(transpose(X,4) ,-7) ) ,12) ,7) ) +transpose((transpose(transpose(transpose(transpose((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(X,7) ) ,-7) ,-7) ,-5) ,-5) +transpose(transpose((X+transpose(X,-5) ) ,-5) ,-5) ) ,-5) ) +transpose(transpose((transpose(((transpose(X,4) |echo(X,4,6) ) +transpose((transpose(transpose(step(X,12) ,-7) ,-7) +transpose(arpeggio(step(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ) ,12) ) ,7) ) ,-7) +echo(transpose(step(transpose(X,-7) ,12) ,-7) ,4,6) ) ,4) ,7) ) ) ,7) ) )
random seed used was 0 EXPR = ((((((transpose(shuffle((((((X|X) +transpose(X,12) ) +transpose(X,12) ) +(arpeggio(X) |transpose((X+X) ,-5) ) ) +echo(transpose(X,4) ,4,6) ) ) ,-5) +transpose(((((((((X+X) +transpose((X+transpose(X,7) ) ,4) ) +transpose(X,7) ) +(X+transpose(transpose(X,-7) ,12) ) ) |X) +transpose(echo(transpose(X,-5) ,4,6) ,12) ) +transpose(transpose(shuffle(transpose(X,-5) ) ,4) ,7) ) +(transpose(step(X,12) ,-5) |((X+transpose(X,12) ) +transpose((X+step(X,12) ) ,7) ) ) ) ,12) ) +((((((((X|X) +transpose(transpose(X,-7) ,7) ) |transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,-7) ) +echo(arpeggio(X) ,4,6) ) +transpose(transpose(((transpose(X,-5) +transpose(((X|X) +(X+transpose(X,12) ) ) ,4) ) +transpose(shuffle(X) ,7) ) ,-5) ,12) ) +transpose(echo((((X|X) +transpose((X|X) ,4) ) +transpose(shuffle(X) ,7) ) ,4,6) ,4) ) +transpose(transpose((transpose(((X+transpose(X,12) ) +(X|X) ) ,-5) +transpose(transpose(X,-5) ,-5) ) ,4) ,7) ) +transpose(transpose(transpose(X,-7) ,4) ,7) ) ) +(((step(step((transpose(X,4) +transpose(X,7) ) ,12) ,12) +transpose(((((X|X) +(X|X) ) +transpose(transpose(arpeggio(shuffle(X) ) ,-7) ,4) ) +transpose(((X+(X+X) ) +((transpose(X,-5) +X) +transpose(echo(((X+transpose(X,4) ) +transpose(X,7) ) ,4,6) ,12) ) ) ,7) ) ,7) ) |((transpose(transpose((X|X) ,4) ,-7) +transpose(transpose((echo(X,4,6) |transpose((X|X) ,-5) ) ,4) ,12) ) +transpose(transpose(transpose((transpose(X,4) +transpose(X,7) ) ,4) ,4) ,7) ) ) |arpeggio(shuffle(((transpose(transpose(X,4) ,-5) +transpose((echo(shuffle(X) ,4,6) |(X|(X+X) ) ) ,12) ) |((arpeggio(X) +transpose((X+transpose(X,12) ) ,12) ) +transpose(step((X+transpose(X,-7) ) ,12) ,7) ) ) ) ) ) ) +(transpose(transpose(transpose(echo((arpeggio(X) |(transpose(X,-7) +transpose(echo((X+((X+transpose(X,4) ) +transpose(X,7) ) ) ,4,6) ,12) ) ) ,4,6) ,-7) ,4) ,-7) +echo(shuffle(((X|X) +(X+transpose(X,12) ) ) ) ,4,6) ) ) +transpose(step(((step((echo(arpeggio((X+X) ) ,4,6) +transpose(shuffle((((transpose(X,4) +transpose(transpose(X,4) ,7) ) +transpose(echo(((X|X) +transpose(transpose(X,4) ,12) ) ,4,6) ,7) ) +((transpose((X+transpose((X+X) ,12) ) ,4) +transpose((((X|X) +transpose(arpeggio(X) ,4) ) +transpose(X,7) ) ,4) ) +transpose((((X+transpose(X,12) ) +transpose(X,7) ) +X) ,7) ) ) ) ,7) ) ,12) +transpose(echo(((transpose(transpose(X,4) ,4) +transpose(X,-7) ) +transpose(((transpose(transpose(X,4) ,-5) +transpose((step(X,12) +transpose(X,7) ) ,4) ) +transpose(echo(transpose(X,-7) ,4,6) ,12) ) ,7) ) ,4,6) ,7) ) +arpeggio(transpose(((((X+transpose(X,7) ) +transpose(transpose(transpose(X,4) ,4) ,4) ) +transpose(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ,7) ) |((X|arpeggio(X) ) +transpose((shuffle(X) +transpose(X,12) ) ,7) ) ) ,-7) ) ) ,12) ,7) ) +transpose(shuffle(((step(arpeggio((transpose(X,4) +transpose((((transpose(X,4) +step(X,12) ) +transpose((X|(X+X) ) ,12) ) +(transpose(X,-7) +transpose((X+transpose(X,12) ) ,12) ) ) ,12) ) ) ,12) |transpose(echo(transpose(step(X,12) ,-5) ,4,6) ,-5) ) +((((((step(X,12) +transpose(transpose(X,4) ,4) ) +transpose(X,7) ) +transpose((transpose(X,4) +transpose(transpose(transpose(X,-7) ,4) ,7) ) ,12) ) +transpose((transpose((X+transpose(X,12) ) ,-5) |X) ,12) ) +transpose(((transpose(X,4) +((step(arpeggio(X) ,12) +transpose(((X+X) +transpose(transpose(X,-7) ,7) ) ,4) ) +transpose(transpose(X,-7) ,7) ) ) +transpose(transpose(shuffle(transpose(X,-5) ) ,4) ,7) ) ,4) ) +transpose(step(transpose(((((X+transpose(transpose(X,4) ,4) ) +transpose((transpose(X,-5) +X) ,7) ) +transpose(transpose(arpeggio(((X+transpose(X,4) ) +transpose(X,7) ) ) ,-7) ,4) ) +transpose(echo(transpose((X+X) ,4) ,4,6) ,7) ) ,-7) ,12) ,7) ) ) ) ,7) )
random seed used was 0 EXPR = (step(transpose((shuffle(shuffle(echo(transpose(step(transpose((shuffle(X) +transpose(X,12) ) ,-7) ,12) ,-7) ,4,6) ) ) |transpose(arpeggio(transpose(transpose(X,-7) ,4) ) ,-7) ) ,-7) ,12) +transpose(transpose(step(transpose(((((((((transpose(shuffle(X) ,4) +transpose(X,7) ) +transpose(arpeggio(transpose(X,-5) ) ,4) ) +transpose((X|X) ,7) ) +transpose(((transpose(X,4) +transpose(arpeggio(((X+transpose(X,4) ) +transpose(X,7) ) ) ,7) ) |transpose(arpeggio(X) ,-7) ) ,12) ) +arpeggio((((echo(X,4,6) +(X|(X+X) ) ) |transpose(echo(transpose(X,4) ,4,6) ,4) ) +arpeggio(X) ) ) ) +((echo(echo(X,4,6) ,4,6) +transpose((transpose(X,4) +transpose(transpose(transpose(echo(X,4,6) ,-7) ,-7) ,7) ) ,12) ) |transpose((step((X+transpose(X,12) ) ,12) +(transpose(X,-7) |X) ) ,4) ) ) |transpose(arpeggio(transpose((transpose((X+echo(X,4,6) ) ,-5) +transpose((((X+X) +transpose(echo(X,4,6) ,4) ) +transpose(shuffle((X+X) ) ,7) ) ,7) ) ,-5) ) ,4) ) |shuffle(arpeggio(step(transpose(((transpose(step((X+X) ,12) ,-7) +transpose(step((shuffle(X) +transpose((X|X) ,7) ) ,12) ,4) ) +transpose(step(transpose(transpose(X,4) ,-5) ,12) ,7) ) ,-5) ,12) ) ) ) ,-5) ,12) ,4) ,-7) )
random seed used was 0

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