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 15 generations the expression "X" became this:
(transpose(step(arpeggio((transpose(transpose(transpose((X+X) ,-5) ,-7) ,-5) +(((((step(transpose(((X+transpose(X,4) ) +transpose((X+transpose(X,7) ) ,7) ) ,4) ,12) +X) |((transpose(X,-5) +transpose(X,4) ) +transpose(echo((X+transpose(X,12) ) ,4,6) ,4) ) ) +transpose((((((X+transpose(X,4) ) +transpose(X,7) ) |X) |transpose(step(X,12) ,-5) ) |((X+(X+transpose(X,7) ) ) |transpose(X,-5) ) ) ,4) ) +transpose(((transpose(X,-5) +((X+transpose(X,7) ) +transpose((X|X) ,7) ) ) +transpose(arpeggio((step(X,12) +X) ) ,7) ) ,7) ) +(transpose((((X+transpose(X,7) ) +transpose(transpose(X,-7) ,12) ) +transpose(transpose(transpose(X,-7) ,4) ,12) ) ,4) +transpose(((X+transpose(transpose(echo(X,4,6) ,-7) ,4) ) +transpose(shuffle(transpose(X,-7) ) ,7) ) ,7) ) ) ) ) ,12) ,4) +transpose(((((echo((shuffle((arpeggio(X) |transpose(transpose(X,-7) ,4) ) ) +(((((X+transpose(X,12) ) +X) +transpose(((((X+shuffle(echo(X,4,6) ) ) +transpose((X+((X+transpose(X,12) ) +transpose(transpose(X,-5) ,12) ) ) ,4) ) +transpose(transpose(X,4) ,7) ) +transpose(step(((X+X) |(X+X) ) ,12) ,12) ) ,7) ) +transpose(transpose(transpose(step((shuffle(transpose(X,4) ) +(X+transpose(X,-7) ) ) ,12) ,4) ,-5) ,4) ) +transpose(transpose(echo(((arpeggio(X) +transpose(transpose(X,-5) ,12) ) +transpose((echo(X,4,6) +(X|X) ) ,12) ) ,4,6) ,-7) ,7) ) ) ,4,6) +transpose((((step(transpose(transpose((step(X,12) +transpose(transpose((shuffle(X) +(echo(X,4,6) +X) ) ,4) ,12) ) ,-7) ,-5) ,12) +transpose((((transpose(transpose(transpose(step(X,12) ,4) ,-5) ,-7) +transpose(transpose(transpose((transpose(transpose(transpose(shuffle(X) ,-7) ,4) ,-5) +transpose((((echo(X,4,6) +transpose(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,-5) ,12) ) +transpose(((X|X) |X) ,4) ) +transpose(echo(transpose(X,4) ,4,6) ,7) ) ,12) ) ,4) ,-5) ,4) ) +transpose(shuffle((transpose(transpose((X+transpose(X,12) ) ,-7) ,-5) +transpose(echo(arpeggio(X) ,4,6) ,-5) ) ) ,7) ) +(arpeggio(echo(transpose(transpose(X,-5) ,-7) ,4,6) ) |(echo((transpose(X,4) +transpose(arpeggio(X) ,7) ) ,4,6) +transpose(transpose(X,4) ,-7) ) ) ) ,4) ) +transpose(arpeggio((arpeggio(shuffle(transpose(shuffle(X) ,4) ) ) |step(transpose(transpose(transpose((X+transpose(X,12) ) ,4) ,-5) ,-5) ,12) ) ) ,7) ) |(transpose(shuffle(transpose(step(transpose(X,-5) ,12) ,-5) ) ,-7) +transpose(transpose(transpose(shuffle(transpose(transpose(X,4) ,4) ) ,4) ,-7) ,12) ) ) ,4) ) +transpose((step(step((transpose(((X|((X+transpose(X,4) ) +transpose(X,7) ) ) +step(((X|X) |step(X,12) ) ,12) ) ,4) +transpose(((((X+step(X,12) ) |transpose((X|(X+transpose(X,12) ) ) ,-5) ) +transpose((transpose(echo(arpeggio(X) ,4,6) ,4) |transpose(((X+X) +step(arpeggio(X) ,12) ) ,4) ) ,4) ) +transpose(transpose((transpose(transpose((X+X) ,-7) ,4) +transpose(((X+transpose((X|X) ,12) ) +transpose(transpose(transpose(X,-7) ,-7) ,7) ) ,12) ) ,4) ,7) ) ,7) ) ,12) ,12) |arpeggio(shuffle((transpose(transpose(transpose(transpose(X,-7) ,-7) ,-7) ,-7) |transpose((shuffle(transpose(transpose((X|X) ,-7) ,-5) ) +transpose(transpose((step(shuffle(X) ,12) |transpose(X,-5) ) ,4) ,7) ) ,4) ) ) ) ) ,7) ) +transpose(transpose(transpose(echo((transpose(transpose(X,-7) ,4) +transpose((X|X) ,12) ) ,4,6) ,-7) ,-5) ,4) ) +transpose((echo(transpose(echo(((transpose(X,-7) |((((X|X) +transpose(step(X,12) ,4) ) +transpose(transpose(X,-5) ,7) ) |((X|(X+X) ) +X) ) ) +transpose((arpeggio((transpose(((X+transpose(X,7) ) +X) ,-5) |transpose(X,4) ) ) |transpose(transpose(transpose(X,4) ,-5) ,-5) ) ,12) ) ,4,6) ,4) ,4,6) +transpose(transpose(((echo(transpose(arpeggio(((transpose(transpose(arpeggio(X) ,4) ,4) +transpose(arpeggio(echo(X,4,6) ) ,4) ) +transpose((arpeggio(((((X+transpose(X,4) ) +transpose(X,7) ) +transpose((X+transpose(X,7) ) ,4) ) +transpose(X,7) ) ) +transpose(transpose(shuffle(X) ,-7) ,12) ) ,7) ) ) ,4) ,4,6) +transpose(shuffle((((transpose(transpose(arpeggio(((transpose(X,-5) +transpose(X,4) ) +transpose((X+X) ,7) ) ) ,4) ,4) +transpose(((X|(X+transpose((X|X) ,12) ) ) +transpose(arpeggio(((X|X) +((X+transpose((X|X) ,4) ) +transpose((X+X) ,7) ) ) ) ,12) ) ,4) ) +transpose(((transpose(transpose(transpose(X,4) ,4) ,-5) +transpose(transpose(X,4) ,7) ) |((((transpose(X,-5) +transpose((X+X) ,7) ) +transpose(X,4) ) +transpose((((X+transpose((X+transpose(X,7) ) ,4) ) +transpose(X,7) ) +transpose(transpose((X+transpose(X,12) ) ,4) ,7) ) ,4) ) +transpose(transpose(X,-5) ,7) ) ) ,7) ) |(transpose((((X+transpose((X+transpose(X,12) ) ,4) ) +transpose(transpose(X,4) ,7) ) |step(transpose(X,4) ,12) ) ,4) |transpose((X+((X+transpose(X,12) ) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ) ) ,4) ) ) ) ,12) ) +transpose(transpose(echo((echo((X+transpose(X,7) ) ,4,6) |(transpose(transpose(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ,4) ,4) +transpose((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(X,7) ) ,-7) ) ) ,4,6) ,4) ,12) ) ,4) ,7) ) ,7) ) ,7) )
random seed used was 736184 EXPR = transpose((((((step(echo(arpeggio(((X+transpose(X,4) ) +transpose(X,7) ) ) ,4,6) ,12) +transpose((((step(X,12) +transpose(transpose(X,4) ,4) ) +transpose(arpeggio(X) ,7) ) |(X|X) ) ,7) ) |arpeggio((arpeggio(((arpeggio(X) +transpose(echo(X,4,6) ,12) ) +transpose(transpose(X,-5) ,7) ) ) +transpose((transpose((X+X) ,-7) +transpose(transpose((X+transpose(X,-5) ) ,4) ,12) ) ,12) ) ) ) +((transpose(arpeggio(transpose(((transpose(transpose(X,-5) ,-7) +transpose(transpose(X,4) ,4) ) +transpose((X+transpose(X,12) ) ,7) ) ,4) ) ,4) +transpose(transpose(transpose(transpose(shuffle((X+transpose(X,7) ) ) ,-7) ,4) ,-5) ,-5) ) +transpose(shuffle(transpose((step((step(step(X,12) ,12) +transpose((X+transpose((X|X) ,7) ) ,12) ) ,12) +(((transpose(X,-5) +transpose(transpose((X+transpose(X,7) ) ,-7) ,7) ) +transpose(transpose((X+X) ,-7) ,4) ) +transpose(X,7) ) ) ,4) ) ,7) ) ) +transpose(echo(((transpose((transpose(transpose(arpeggio(transpose(X,-7) ) ,-7) ,-5) |(((transpose(((X+X) +transpose((X|X) ,7) ) ,-7) +transpose(((X+transpose(X,7) ) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,7) ) ,12) ) +arpeggio(step(transpose(X,-5) ,12) ) ) |transpose((transpose(X,4) +transpose(shuffle(((X+transpose(X,4) ) +transpose(X,7) ) ) ,12) ) ,-5) ) ) ,-5) +transpose(((arpeggio((X|X) ) +(((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(X,4) ) +transpose(X,7) ) +transpose(transpose(X,4) ,12) ) ) +(((X+transpose(X,4) ) +transpose(X,7) ) |X) ) ,4) ) +transpose(echo((((X+transpose(X,12) ) |arpeggio(X) ) +transpose(X,-5) ) ,4,6) ,7) ) ,4,6) ,7) ) +transpose(transpose((((((step(echo((X+X) ,4,6) ,12) +transpose(transpose(transpose((shuffle(transpose(X,-5) ) +transpose((step(X,12) +(transpose(X,4) |transpose(X,-5) ) ) ,7) ) ,-5) ,-5) ,7) ) +transpose((echo(transpose(transpose(((X+X) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,7) ) ,-5) ,-5) ,4,6) +transpose(transpose(transpose(step((transpose(step(X,12) ,-5) +transpose(transpose(X,-7) ,7) ) ,12) ,-5) ,-7) ,12) ) ,12) ) +transpose(arpeggio(arpeggio(step((arpeggio(X) +transpose(X,12) ) ,12) ) ) ,4) ) +transpose(((echo(transpose(((shuffle(X) +transpose(transpose(X,-5) ,7) ) |transpose(X,4) ) ,4) ,4,6) +transpose(echo((transpose(transpose(echo(((X+transpose(X,4) ) +transpose(X,7) ) ,4,6) ,-7) ,4) +transpose((((X+transpose(X,12) ) +transpose(echo(X,4,6) ,12) ) |transpose(X,-5) ) ,12) ) ,4,6) ,7) ) +(((transpose(X,4) +(X+X) ) |(transpose(echo(X,4,6) ,-7) +transpose(step(X,12) ,7) ) ) +step(transpose(transpose(X,4) ,4) ,12) ) ) ,4) ) +transpose(shuffle((((transpose(arpeggio((transpose(shuffle(X) ,4) +transpose(transpose((X+X) ,-7) ,7) ) ) ,4) +transpose((echo(echo(X,4,6) ,4,6) +transpose(transpose(echo(arpeggio(X) ,4,6) ,-5) ,12) ) ,7) ) |(((shuffle(X) +transpose((X+X) ,4) ) +transpose((X+X) ,7) ) |transpose((X+(X+transpose(X,12) ) ) ,4) ) ) |(transpose((transpose(step(((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(X,4) ) +transpose(transpose(X,-7) ,7) ) ,12) ,-7) |((X|X) +transpose(arpeggio(transpose(X,-5) ) ,12) ) ) ,4) |echo(transpose((transpose(((X+transpose(X,7) ) |((X+transpose(X,4) ) +transpose(X,7) ) ) ,-5) |(transpose(X,4) +transpose(shuffle(X) ,12) ) ) ,4) ,4,6) ) ) ) ,7) ) ,4) ,7) ) ,-5)
random seed used was 0 EXPR = step((((transpose((((shuffle(transpose((transpose(X,-5) +X) ,-5) ) |transpose(echo(((X+((X+transpose(X,4) ) +transpose(X,7) ) ) +(((X|X) +transpose(arpeggio(X) ,7) ) |arpeggio(transpose(X,4) ) ) ) ,4,6) ,-5) ) |(step((X+transpose(X,7) ) ,12) +transpose(shuffle(((arpeggio(X) +shuffle(X) ) +transpose((X+transpose(X,7) ) ,4) ) ) ,7) ) ) +transpose(step(transpose(((transpose(transpose(X,-5) ,-7) +transpose(transpose(((X|X) +transpose(X,7) ) ,4) ,4) ) +transpose(step((transpose(X,4) +transpose(X,4) ) ,12) ,7) ) ,-5) ,12) ,7) ) ,4) +transpose(transpose(arpeggio(shuffle((((transpose(((((transpose(X,4) +transpose(X,-7) ) +transpose((X|transpose(X,-5) ) ,4) ) +transpose(transpose(transpose(X,-7) ,-7) ,7) ) +transpose((echo(X,4,6) +transpose((transpose(X,4) |transpose(X,-7) ) ,12) ) ,12) ) ,-5) |(shuffle(((transpose((X+transpose(X,12) ) ,4) +transpose((X+transpose(X,12) ) ,4) ) +transpose(((echo(((X+transpose(X,4) ) +transpose(X,7) ) ,4,6) +transpose((transpose(X,-5) +(X+X) ) ,4) ) +transpose(transpose(X,4) ,7) ) ,7) ) ) +(arpeggio(transpose(X,-7) ) |((X+transpose(transpose(X,-7) ,12) ) |((X+X) |X) ) ) ) ) +transpose((((transpose(transpose(X,-7) ,-5) +transpose(transpose((((X+transpose(X,7) ) +transpose((X+transpose(X,7) ) ,4) ) +transpose(arpeggio(X) ,7) ) ,4) ,4) ) +transpose(transpose((X|X) ,4) ,7) ) +transpose((transpose((X|transpose(X,-7) ) ,4) +transpose(arpeggio(shuffle(shuffle(X) ) ) ,7) ) ,7) ) ,4) ) +transpose(((transpose(X,4) +transpose(((transpose(X,4) +transpose(X,4) ) +transpose((transpose(X,4) +(X+X) ) ,7) ) ,4) ) +((((X+transpose(X,7) ) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,4) ) +transpose((transpose(X,4) |(X+transpose(X,7) ) ) ,7) ) +transpose(echo(((step(X,12) +transpose((X+X) ,4) ) +transpose(transpose(X,4) ,7) ) ,4,6) ,7) ) ) ,7) ) ) ) ,-7) ,12) ) +transpose(transpose(((transpose((transpose((step(X,12) +transpose(transpose(transpose(X,4) ,-5) ,7) ) ,-5) |transpose(arpeggio((((X+X) +transpose(arpeggio(X) ,4) ) +transpose(arpeggio(X) ,7) ) ) ,4) ) ,-7) +transpose(((transpose(step(arpeggio(X) ,12) ,4) +transpose(shuffle(((X+transpose(X,4) ) +transpose(echo(((X+transpose(X,4) ) +transpose(X,7) ) ,4,6) ,7) ) ) ,4) ) +transpose(arpeggio(shuffle(X) ) ,7) ) ,4) ) +transpose(arpeggio(transpose(((X+transpose((X|echo(X,4,6) ) ,4) ) +transpose(transpose(echo(X,4,6) ,4) ,7) ) ,-7) ) ,7) ) ,-5) ,4) ) +transpose((((step((shuffle(((echo((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(transpose(X,-7) ,12) ) ,4,6) +X) +(((X+transpose(X,7) ) |(X+X) ) |transpose((X+transpose(X,12) ) ,-5) ) ) ) +transpose(transpose(echo((arpeggio(X) |(arpeggio(X) +(X+transpose(X,12) ) ) ) ,4,6) ,-7) ,12) ) ,12) +transpose((((transpose((X|X) ,-5) +transpose(transpose(transpose(X,-7) ,-5) ,12) ) +transpose(transpose(arpeggio(X) ,4) ,4) ) +transpose((transpose(echo((((X+transpose(X,-7) ) +transpose(shuffle(transpose(arpeggio(X) ,4) ) ,4) ) +transpose(transpose(X,-5) ,7) ) ,4,6) ,-5) +(transpose(((X+transpose(X,12) ) +transpose((X+transpose(X,7) ) ,4) ) ,-5) |echo(transpose(shuffle(X) ,-7) ,4,6) ) ) ,7) ) ,7) ) +transpose((step(((step((transpose(arpeggio((X+X) ) ,-5) |transpose(arpeggio(X) ,4) ) ,12) +(transpose(step(X,12) ,-7) +(X|X) ) ) +transpose(((transpose(transpose(transpose(X,4) ,4) ,-7) +transpose((echo((step(X,12) +(X+X) ) ,4,6) +transpose(echo(X,4,6) ,12) ) ,7) ) +(X+transpose((X+X) ,7) ) ) ,12) ) ,12) +(((echo(arpeggio(step(transpose(transpose((X+echo(arpeggio(X) ,4,6) ) ,4) ,4) ,12) ) ,4,6) +transpose(shuffle((transpose(transpose(X,4) ,-7) +transpose(step((transpose(X,-5) +transpose((X+transpose(X,12) ) ,7) ) ,12) ,-7) ) ) ,4) ) +transpose((transpose((arpeggio(X) |transpose(transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,-5) ,-5) ) ,-5) +transpose(transpose(transpose(X,4) ,-7) ,12) ) ,7) ) +transpose((transpose(step((transpose((X|X) ,-5) |step(((X|X) +transpose(X,4) ) ,12) ) ,12) ,-7) +transpose((step(transpose(transpose((X+transpose(X,-5) ) ,-5) ,-7) ,12) +transpose((transpose(X,4) |(((((X+transpose(X,7) ) +transpose(echo(X,4,6) ,7) ) |X) +transpose(transpose(transpose((X+transpose(X,12) ) ,4) ,-7) ,7) ) |(transpose((transpose(X,4) +echo(X,4,6) ) ,-7) |(arpeggio(X) |arpeggio(X) ) ) ) ) ,12) ) ,7) ) ,12) ) ) ,4) ) +transpose(transpose(transpose(((transpose(transpose(X,-5) ,-5) +transpose(echo(X,4,6) ,12) ) +transpose(echo(X,4,6) ,4) ) ,4) ,-5) ,7) ) ,7) ) ,12)
random seed used was 0

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