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:
shuffle(transpose(shuffle((((transpose(shuffle(((shuffle(shuffle(transpose(((X+X) |X) ,-5) ) ) +transpose(step(((transpose(X,-5) |X) +transpose(step((step(X,12) +transpose(echo(X,4,6) ,12) ) ,12) ,7) ) ,12) ,12) ) |((transpose(echo((((X+transpose(X,4) ) +transpose(X,7) ) +transpose((X+transpose(step(X,12) ,12) ) ,7) ) ,4,6) ,4) |arpeggio(step(shuffle(X) ,12) ) ) |arpeggio((transpose((transpose((X+X) ,4) |shuffle(transpose(transpose(X,-7) ,4) ) ) ,4) |step(arpeggio((X|transpose(X,4) ) ) ,12) ) ) ) ) ) ,4) +((transpose(step(transpose(step((X+transpose(X,12) ) ,12) ,-7) ,12) ,4) +(echo((transpose(((transpose(X,4) +transpose(transpose(X,4) ,4) ) +transpose(arpeggio(step(X,12) ) ,7) ) ,-5) |transpose(((arpeggio(X) +transpose((X+transpose(X,7) ) ,4) ) +transpose(shuffle((X|X) ) ,7) ) ,-7) ) ,4,6) |echo((step(shuffle((step(X,12) +transpose(X,7) ) ) ,12) +transpose(shuffle(arpeggio(transpose(transpose(X,-5) ,4) ) ) ,7) ) ,4,6) ) ) +transpose(((shuffle(arpeggio(((transpose(transpose(X,-7) ,-5) +transpose(transpose(arpeggio(X) ,-7) ,12) ) +(transpose(shuffle(echo(X,4,6) ) ,4) +transpose(shuffle(shuffle(transpose(X,-5) ) ) ,7) ) ) ) ) +transpose(transpose((shuffle((shuffle(X) +transpose(transpose(X,-5) ,12) ) ) +step((X+transpose((X|X) ,12) ) ,12) ) ,-5) ,4) ) +transpose(transpose((transpose(echo(transpose((X+transpose(X,7) ) ,-5) ,4,6) ,-7) +transpose(((shuffle(X) +transpose(arpeggio(X) ,4) ) +transpose((X+transpose(X,12) ) ,7) ) ,-5) ) ,-5) ,7) ) ,4) ) ) |transpose(((transpose(step((step(transpose(transpose(X,4) ,-5) ,12) |step(echo(echo(shuffle(arpeggio(X) ) ,4,6) ,4,6) ,12) ) ,12) ,4) +transpose(shuffle(step((((arpeggio(shuffle(X) ) |(transpose(X,4) +X) ) +transpose(arpeggio(transpose((X+transpose(X,12) ) ,4) ) ,4) ) +transpose(transpose(((transpose(shuffle((X+transpose(X,12) ) ) ,-5) +transpose(transpose(arpeggio(X) ,-7) ,4) ) +transpose(transpose((((X+X) +transpose(shuffle(X) ,7) ) |((X|X) +step(X,12) ) ) ,-5) ,7) ) ,-7) ,7) ) ,12) ) ,4) ) +transpose(arpeggio((((arpeggio(echo(transpose(shuffle(((transpose(transpose(X,-7) ,4) +transpose(((X+transpose(X,7) ) |X) ,4) ) +transpose(((arpeggio(X) +X) |step(transpose(X,4) ,12) ) ,7) ) ) ,4) ,4,6) ) +transpose(shuffle(arpeggio(step((transpose(X,-7) +transpose(transpose(step(X,12) ,4) ,12) ) ,12) ) ) ,-7) ) +transpose(arpeggio(shuffle(transpose((((((transpose(X,-5) +transpose(step(X,12) ,7) ) +transpose((X+X) ,4) ) +transpose((transpose(X,-5) |step(X,12) ) ,7) ) +transpose(((echo(X,4,6) +transpose((arpeggio(X) +(X+transpose(X,7) ) ) ,4) ) +transpose((X+transpose(X,7) ) ,7) ) ,4) ) +transpose((step(X,12) +transpose(shuffle(transpose(X,-7) ) ,7) ) ,7) ) ,4) ) ) ,4) ) +transpose(arpeggio(((arpeggio(((transpose(X,4) +transpose((((X+transpose(shuffle(X) ,4) ) +transpose(transpose(X,-7) ,7) ) +transpose(arpeggio(X) ,7) ) ,12) ) +((X+transpose((X+transpose(X,12) ) ,7) ) +transpose(X,12) ) ) ) +transpose(shuffle(((step(X,12) +transpose(transpose(arpeggio(X) ,4) ,7) ) +transpose(echo((shuffle(X) |shuffle(X) ) ,4,6) ,7) ) ) ,4) ) +transpose(transpose(step((transpose(X,4) +(X+transpose(X,12) ) ) ,12) ,4) ,7) ) ) ,7) ) ) ,7) ) ,4) ) |transpose(transpose(((shuffle(echo(transpose(step(echo((step((arpeggio(step((X+transpose(X,7) ) ,12) ) +transpose((X|X) ,-5) ) ,12) |transpose(step((step(X,12) +transpose(transpose(X,4) ,12) ) ,12) ,4) ) ,4,6) ,12) ,4) ,4,6) ) +transpose(shuffle(step(shuffle((arpeggio(shuffle(shuffle(X) ) ) +(((echo(transpose(step(X,12) ,-5) ,4,6) +transpose(transpose(arpeggio(((X+transpose(X,7) ) +transpose(X,7) ) ) ,-7) ,12) ) +transpose(((transpose((X+transpose(arpeggio(X) ,7) ) ,4) |shuffle(step(X,12) ) ) |((transpose(X,4) |(X|X) ) +echo(arpeggio(X) ,4,6) ) ) ,4) ) +transpose(shuffle(X) ,7) ) ) ) ,12) ) ,4) ) +transpose(transpose(echo(echo(echo(transpose(arpeggio(((X+transpose(transpose(X,4) ,12) ) +(transpose(X,-7) +X) ) ) ,-7) ,4,6) ,4,6) ,4,6) ,4) ,7) ) ,4) ,4) ) ) ,-7) )
random seed used was 143009853 EXPR = echo(arpeggio(transpose(transpose(step(((step(transpose(((transpose((((transpose(((transpose(X,-5) +transpose(step(X,12) ,4) ) +transpose(step(X,12) ,7) ) ,4) +transpose(echo(transpose(transpose(X,-7) ,-5) ,4,6) ,4) ) +transpose(transpose((transpose(transpose(X,-7) ,-7) |shuffle(arpeggio(X) ) ) ,-5) ,7) ) +(arpeggio(transpose(step(X,12) ,4) ) +transpose((arpeggio((X|X) ) |(transpose(X,-5) +transpose((X+transpose(X,12) ) ,7) ) ) ,12) ) ) ,-7) +transpose((shuffle(transpose(((X+transpose(X,12) ) +transpose(shuffle(X) ,7) ) ,-5) ) |shuffle(shuffle(step((X+(X+X) ) ,12) ) ) ) ,4) ) +transpose(step(arpeggio(transpose((transpose(step(X,12) ,-7) +transpose(transpose(X,4) ,12) ) ,-7) ) ,12) ,7) ) ,-5) ,12) |shuffle(shuffle((step((transpose((step(X,12) |(((X+transpose(X,4) ) +transpose(X,7) ) +((X+transpose(X,4) ) +transpose(X,7) ) ) ) ,4) |shuffle(step(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ) ) ,12) +(((arpeggio(transpose((arpeggio(X) +transpose(X,7) ) ,-7) ) +transpose((step(shuffle(X) ,12) |transpose(echo((X+X) ,4,6) ,4) ) ,7) ) +transpose(echo(step(step(shuffle(transpose(transpose(X,-5) ,-7) ) ,12) ,12) ,4,6) ,4) ) +transpose((step(transpose(((transpose(X,-7) +transpose((shuffle(X) +transpose(X,12) ) ,4) ) +transpose(((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(shuffle(X) ,4) ) +transpose(step(X,12) ,7) ) ,7) ) ,4) ,12) +transpose(transpose((arpeggio(arpeggio(X) ) +transpose((transpose((X+transpose(X,7) ) ,-7) |step(transpose(arpeggio(X) ,-7) ,12) ) ,7) ) ,-5) ,12) ) ,7) ) ) ) ) ) |arpeggio(step((transpose(transpose(arpeggio((shuffle(X) +step(X,12) ) ) ,-5) ,-5) |((arpeggio(transpose(step(X,12) ,-5) ) +transpose(shuffle(arpeggio((transpose(transpose(X,-5) ,-5) +transpose(echo((X+transpose(X,12) ) ,4,6) ,12) ) ) ) ,4) ) +transpose(arpeggio(transpose(step(transpose(transpose(X,-5) ,-5) ,12) ,-7) ) ,7) ) ) ,12) ) ) ,12) ,-7) ,4) ) ,4,6)
random seed used was 0 EXPR = (((step(((((transpose(((transpose(transpose(shuffle(X) ,-5) ,-7) |step(transpose(arpeggio(X) ,-7) ,12) ) |shuffle(step(step((arpeggio(X) +transpose((step(X,12) |(X+transpose(transpose(X,-7) ,12) ) ) ,12) ) ,12) ,12) ) ) ,4) +transpose(transpose(transpose((shuffle((shuffle(X) +transpose((transpose((X+X) ,-5) +transpose(echo((X+X) ,4,6) ,7) ) ,12) ) ) +transpose((((transpose(transpose(X,-5) ,-7) |(((transpose((X|X) ,-7) +transpose((X+step(X,12) ) ,4) ) +transpose(step((X+X) ,12) ,7) ) +transpose(X,12) ) ) +transpose(transpose((step(arpeggio(((X+X) +transpose(step(X,12) ,7) ) ) ,12) +(step(transpose(X,-5) ,12) +transpose(transpose(X,-7) ,-7) ) ) ,4) ,4) ) +transpose(arpeggio(X) ,7) ) ,7) ) ,4) ,-5) ,4) ) +transpose(step(((transpose((((X+X) +transpose(step(X,12) ,4) ) +transpose((X+X) ,7) ) ,4) +((((((shuffle(X) +transpose(X,12) ) |X) +transpose((X|X) ,12) ) +transpose(transpose(arpeggio(X) ,4) ,4) ) +transpose(step(arpeggio((X+X) ) ,12) ,7) ) +transpose((arpeggio(shuffle(transpose(X,-7) ) ) +transpose(shuffle(X) ,12) ) ,12) ) ) +transpose(arpeggio((arpeggio((X+transpose(X,7) ) ) +transpose(transpose(arpeggio(X) ,4) ,7) ) ) ,12) ) ,12) ,7) ) +transpose(transpose(arpeggio(arpeggio(shuffle(transpose(transpose(((X|X) |((X+transpose(X,7) ) +((X|X) +transpose(transpose(X,4) ,7) ) ) ) ,-7) ,4) ) ) ) ,-5) ,4) ) +transpose(transpose(step(transpose(arpeggio((transpose((step(transpose(X,4) ,12) |arpeggio(X) ) ,-5) +(transpose((X+X) ,-7) +transpose(X,4) ) ) ) ,-5) ,12) ,-7) ,7) ) ,12) +transpose((arpeggio((step(((arpeggio(arpeggio((echo(X,4,6) +transpose(X,12) ) ) ) +transpose(transpose(transpose(transpose(transpose(X,-7) ,-7) ,4) ,-7) ,4) ) |transpose(((arpeggio(X) +transpose((echo((step(X,12) +transpose(X,12) ) ,4,6) +transpose(X,4) ) ,4) ) +transpose(step(arpeggio(X) ,12) ,7) ) ,-7) ) ,12) +transpose(arpeggio(step((arpeggio(step((step(X,12) +arpeggio(arpeggio(X) ) ) ,12) ) |(shuffle((echo(X,4,6) |transpose(X,4) ) ) +(shuffle(transpose(transpose(X,-7) ,4) ) +transpose((shuffle(transpose(X,-5) ) +transpose(transpose((transpose(X,-7) +X) ,-7) ,12) ) ,12) ) ) ) ,12) ) ,12) ) ) +transpose(shuffle(arpeggio(transpose(step(step(transpose(arpeggio(transpose((X|arpeggio(echo(X,4,6) ) ) ,4) ) ,-5) ,12) ,12) ,-5) ) ) ,12) ) ,7) ) +transpose((arpeggio((step((((transpose(echo((X+transpose(transpose(step(X,12) ,-5) ,12) ) ,4,6) ,-7) +transpose(transpose(shuffle(transpose(X,4) ) ,-7) ,7) ) |(shuffle(((transpose(arpeggio(step(X,12) ) ,4) |echo((X+transpose(X,12) ) ,4,6) ) +transpose((transpose(arpeggio(X) ,4) |arpeggio(echo(X,4,6) ) ) ,12) ) ) +shuffle((echo(X,4,6) |X) ) ) ) |transpose((arpeggio(((step(arpeggio(X) ,12) +transpose((step(transpose(X,-5) ,12) |((transpose((X|X) ,4) +transpose(step(X,12) ,4) ) +transpose((transpose(X,-7) |(X+X) ) ,7) ) ) ,4) ) +transpose(step(arpeggio(transpose(X,4) ) ,12) ,7) ) ) +transpose(step(transpose(transpose((X|X) ,-5) ,4) ,12) ,7) ) ,-5) ) ,12) +shuffle(((shuffle(arpeggio(((shuffle(arpeggio(((X+transpose((X+X) ,4) ) +transpose(transpose(X,-7) ,7) ) ) ) +X) |echo(transpose(echo((X+transpose(X,12) ) ,4,6) ,4) ,4,6) ) ) ) |step(shuffle((step(transpose((transpose(X,-7) +transpose(arpeggio(X) ,12) ) ,-7) ,12) +transpose(((X+transpose(arpeggio(X) ,4) ) +transpose(((X+transpose(X,4) ) +transpose((X+transpose(X,12) ) ,7) ) ,7) ) ,7) ) ) ,12) ) +transpose((((((transpose(transpose(transpose(((X+transpose(transpose(X,4) ,4) ) +transpose(X,7) ) ,-5) ,-5) ,4) |((arpeggio(shuffle(((transpose(X,-7) +X) +X) ) ) +transpose(((transpose(step(X,12) ,-7) +transpose(step(transpose(transpose(transpose(X,4) ,4) ,4) ,12) ,4) ) +transpose(transpose(transpose(((X+transpose(transpose(X,4) ,4) ) +transpose(arpeggio(X) ,7) ) ,-5) ,-5) ,7) ) ,4) ) +transpose(transpose(arpeggio(step(arpeggio(transpose(X,4) ) ,12) ) ,4) ,7) ) ) +transpose(arpeggio(step(X,12) ) ,4) ) +transpose(arpeggio(shuffle(transpose(X,-5) ) ) ,7) ) +transpose(echo(((step(X,12) |step((arpeggio(X) +transpose(transpose(X,4) ,12) ) ,12) ) +transpose(echo(transpose(transpose(((X+X) +arpeggio(X) ) ,4) ,-5) ,4,6) ,7) ) ,4,6) ,4) ) +transpose(shuffle(transpose(arpeggio(shuffle(echo(echo(X,4,6) ,4,6) ) ) ,-5) ) ,7) ) ,12) ) ) ) ) +transpose(transpose(step(((shuffle(transpose(transpose(step(transpose(transpose(step((X+X) ,12) ,-5) ,4) ,12) ,-7) ,-7) ) |step((transpose(((((((X+(X+X) ) +transpose((X|shuffle(X) ) ,4) ) +transpose(X,7) ) +transpose(transpose(transpose(X,-5) ,-5) ,4) ) +transpose(arpeggio((transpose(X,-7) +transpose(X,12) ) ) ,7) ) +(transpose(step(X,12) ,-5) |step(step(X,12) ,12) ) ) ,-7) |(transpose(X,4) +transpose(step(((((X+transpose(X,12) ) |transpose(X,4) ) +transpose(arpeggio(shuffle(X) ) ,4) ) +transpose(((X+X) |X) ,7) ) ,12) ,7) ) ) ,12) ) |((((((shuffle(arpeggio((arpeggio(transpose(X,-7) ) +transpose(transpose(shuffle(X) ,4) ,12) ) ) ) +(shuffle(transpose(arpeggio((transpose(X,4) +(((X+transpose(X,12) ) +transpose(X,4) ) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,7) ) ) ) ,4) ) |shuffle(shuffle(arpeggio(transpose(X,-7) ) ) ) ) ) +transpose(step(shuffle(transpose(shuffle(arpeggio(X) ) ,4) ) ,12) ,4) ) +transpose(transpose(transpose(((step(transpose(arpeggio((arpeggio(X) |X) ) ,-7) ,12) +transpose(((step(X,12) +transpose(((step(X,12) +transpose(X,7) ) +step(transpose(X,4) ,12) ) ,4) ) +transpose(shuffle(X) ,7) ) ,4) ) +transpose(shuffle((step((X+X) ,12) +arpeggio((X+transpose(arpeggio(X) ,12) ) ) ) ) ,7) ) ,4) ,-5) ,7) ) +transpose(transpose(step(((((((transpose(arpeggio(echo((X+transpose(X,12) ) ,4,6) ) ,4) +transpose(transpose((echo(X,4,6) +transpose(arpeggio((X|X) ) ,12) ) ,4) ,7) ) +transpose(step(arpeggio(arpeggio((X+transpose(X,7) ) ) ) ,12) ,4) ) +transpose((arpeggio(step(transpose(X,-7) ,12) ) +arpeggio(X) ) ,7) ) +transpose(arpeggio(echo((shuffle(X) +transpose(X,7) ) ,4,6) ) ,12) ) +transpose((echo(transpose(X,-5) ,4,6) +transpose((((X+transpose(X,4) ) +transpose(X,7) ) |transpose(shuffle(X) ,4) ) ,7) ) ,4) ) +transpose(shuffle(arpeggio((step(step((X|X) ,12) ,12) +transpose(X,-7) ) ) ) ,7) ) ,12) ,4) ,4) ) +transpose((arpeggio(transpose(arpeggio((X+X) ) ,4) ) |((transpose(transpose((step(shuffle(X) ,12) +arpeggio(shuffle(X) ) ) ,-7) ,-7) +transpose((step(step(transpose(X,4) ,12) ,12) +transpose((X+transpose(transpose(echo(X,4,6) ,-5) ,12) ) ,12) ) ,4) ) +transpose(((echo((arpeggio(X) |(shuffle(step(X,12) ) +transpose((shuffle(X) +(X+transpose(X,12) ) ) ,12) ) ) ,4,6) +transpose(arpeggio(transpose(transpose(X,-5) ,4) ) ,4) ) +transpose((((X|transpose(X,-7) ) +transpose(arpeggio(X) ,-5) ) +transpose(transpose((((X+transpose(X,4) ) +transpose(X,7) ) +transpose(X,12) ) ,4) ,7) ) ,7) ) ,7) ) ) ,7) ) +transpose(shuffle((echo(step(((X+transpose(X,7) ) |transpose(X,-5) ) ,12) ,4,6) +transpose(((X+transpose(transpose(step(transpose(X,-5) ,12) ,4) ,7) ) +transpose((step((X+X) ,12) +(X|X) ) ,12) ) ,-5) ) ) ,7) ) ) ,12) ,-7) ,12) ) ,7) ) +transpose(transpose(shuffle(transpose(step(arpeggio(shuffle((step(arpeggio(arpeggio((echo((shuffle(step((((X+transpose(X,12) ) +transpose(transpose(X,4) ,4) ) +transpose(X,7) ) ,12) ) +(transpose(transpose(shuffle(X) ,-7) ,4) +transpose(transpose(X,4) ,12) ) ) ,4,6) +((step(X,12) +transpose((step(X,12) +transpose((X+X) ,12) ) ,12) ) +((shuffle(X) +transpose(X,-5) ) +transpose(transpose(echo(X,4,6) ,4) ,12) ) ) ) ) ) ,12) +transpose(((transpose(transpose((transpose(((X+transpose(transpose(X,-5) ,4) ) +transpose(X,7) ) ,-7) |arpeggio(echo(X,4,6) ) ) ,-7) ,4) +transpose(((step(transpose(shuffle(arpeggio(X) ) ,4) ,12) +shuffle(step(transpose(shuffle(X) ,4) ,12) ) ) +step((transpose((arpeggio(X) +transpose(X,7) ) ,4) +step(transpose(transpose(step(X,12) ,4) ,-5) ,12) ) ,12) ) ,12) ) +transpose((transpose(transpose(echo(((arpeggio(shuffle(X) ) +transpose(step(transpose(X,-7) ,12) ,4) ) +transpose((((X+transpose(X,4) ) +transpose(arpeggio(X) ,7) ) |step(X,12) ) ,7) ) ,4,6) ,-7) ,-7) +transpose((echo((X+transpose(arpeggio(X) ,12) ) ,4,6) +transpose((step(X,12) +shuffle(((X|X) +transpose((X+transpose(X,7) ) ,4) ) ) ) ,12) ) ,-5) ) ,12) ) ,7) ) ) ) ,12) ,4) ) ,-5) ,12) )
random seed used was 0 EXPR = step(((shuffle(transpose((arpeggio(echo((echo((arpeggio(X) +transpose(shuffle(step(X,12) ) ,12) ) ,4,6) +transpose(transpose(shuffle(transpose((step(shuffle(X) ,12) |(arpeggio((X+(X+X) ) ) |(X|transpose(transpose(arpeggio(X) ,-7) ,-5) ) ) ) ,4) ) ,4) ,7) ) ,4,6) ) |transpose(shuffle((transpose(arpeggio(shuffle(shuffle((X+transpose(X,12) ) ) ) ) ,-5) +transpose(transpose(arpeggio((arpeggio(arpeggio(step(X,12) ) ) +transpose(X,7) ) ) ,4) ,-7) ) ) ,-5) ) ,4) ) +transpose(shuffle(transpose(shuffle((step(transpose(arpeggio((step((((X+transpose(X,4) ) +transpose((X+X) ,7) ) |shuffle(step(X,12) ) ) ,12) |arpeggio(((((X|X) +transpose(X,-7) ) +arpeggio(step(X,12) ) ) |(transpose(shuffle(X) ,4) +transpose(echo(X,4,6) ,7) ) ) ) ) ) ,-5) ,12) +transpose(transpose(transpose(shuffle((((step(shuffle(X) ,12) +transpose(((transpose((transpose(transpose(X,4) ,4) +transpose(X,7) ) ,4) +transpose(shuffle(transpose(step(X,12) ,-7) ) ,4) ) +transpose((X+transpose(X,12) ) ,7) ) ,12) ) +transpose(shuffle(transpose((transpose(X,4) +transpose(X,-5) ) ,4) ) ,4) ) +transpose((((((X+transpose(X,12) ) +step(X,12) ) |transpose((transpose(X,-7) +shuffle(X) ) ,-5) ) +transpose((step(step(X,12) ,12) |(step((X+X) ,12) +(step(X,12) +transpose(X,7) ) ) ) ,4) ) +transpose(shuffle((X|X) ) ,7) ) ,7) ) ) ,-5) ,-7) ,12) ) ) ,-5) ) ,4) ) +transpose(((transpose(arpeggio(step(arpeggio((transpose(transpose(step(transpose(transpose(step(shuffle(X) ,12) ,-7) ,-7) ,12) ,-5) ,-5) +(step(X,12) +transpose((arpeggio(arpeggio(shuffle(arpeggio(((X+transpose(X,4) ) +transpose(X,7) ) ) ) ) ) +arpeggio(arpeggio((shuffle(arpeggio(X) ) +transpose((X+X) ,12) ) ) ) ) ,-5) ) ) ) ,12) ) ,-7) +(step((((shuffle((X+((step(X,12) |X) +X) ) ) +transpose(step(transpose(transpose(shuffle(X) ,4) ,-7) ,12) ,4) ) +transpose(transpose((echo(step(((X+transpose(arpeggio((X+transpose(X,7) ) ) ,4) ) +transpose(shuffle(X) ,7) ) ,12) ,4,6) +transpose((step(((X+transpose(arpeggio(X) ,7) ) +transpose(((X+X) |step(arpeggio(X) ,12) ) ,7) ) ,12) |transpose(((((transpose(X,-5) +transpose(X,12) ) +transpose(step(step(X,12) ,12) ,4) ) +transpose(((X+transpose((X+transpose(X,12) ) ,4) ) +transpose(X,7) ) ,7) ) +transpose(((X|X) +X) ,12) ) ,-7) ) ,7) ) ,4) ,7) ) +transpose(transpose(arpeggio(shuffle(((step(shuffle(((((X+transpose(X,12) ) +transpose(shuffle(X) ,4) ) +transpose(echo(transpose(X,-7) ,4,6) ,7) ) +(X+transpose((X+transpose(X,12) ) ,7) ) ) ) ,12) +transpose(arpeggio((shuffle((arpeggio(step(X,12) ) +transpose(((transpose(X,-7) +transpose((X+transpose(X,12) ) ,7) ) +transpose((shuffle(X) |arpeggio(X) ) ,12) ) ,7) ) ) +transpose((shuffle(X) +transpose(X,12) ) ,12) ) ) ,4) ) +transpose(step((echo(shuffle(arpeggio(shuffle(X) ) ) ,4,6) |arpeggio(step(X,12) ) ) ,12) ,7) ) ) ) ,-5) ,7) ) ,12) |transpose((arpeggio(shuffle(shuffle(transpose(shuffle(arpeggio((X+transpose(transpose(X,4) ,7) ) ) ) ,-7) ) ) ) |(step(transpose(transpose((arpeggio(shuffle(((X+transpose(X,4) ) +transpose(X,7) ) ) ) +(arpeggio((X+transpose(X,12) ) ) |(X+transpose(X,12) ) ) ) ,4) ,-7) ,12) +(((echo(arpeggio(X) ,4,6) +transpose(step(((X+transpose(shuffle(X) ,4) ) +transpose(transpose(step(X,12) ,-5) ,7) ) ,12) ,4) ) +transpose(transpose(transpose(transpose(X,-5) ,4) ,-5) ,7) ) +((transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,-5) |step((X|X) ,12) ) +arpeggio(transpose(arpeggio((X|X) ) ,-5) ) ) ) ) ) ,-7) ) ) |(transpose(((shuffle(transpose((((step(X,12) +transpose(((shuffle(transpose((X+X) ,-7) ) +transpose(transpose(step(X,12) ,-7) ,4) ) +transpose(arpeggio(arpeggio(X) ) ,7) ) ,4) ) +transpose(transpose(arpeggio(step(arpeggio(X) ,12) ) ,4) ,7) ) +transpose((arpeggio((step(X,12) +arpeggio(arpeggio(arpeggio(X) ) ) ) ) |((transpose(step(X,12) ,4) +transpose(arpeggio(X) ,4) ) +transpose(((transpose(X,4) +transpose(transpose(X,4) ,4) ) +transpose(transpose(X,4) ,7) ) ,7) ) ) ,-5) ) ,-7) ) +transpose((transpose((((transpose((transpose(step(X,12) ,-7) |(transpose(transpose(X,-5) ,-5) +transpose(arpeggio(transpose((X|X) ,4) ) ,12) ) ) ,-5) +transpose((transpose(((X|transpose(X,4) ) +shuffle((X+transpose(X,-7) ) ) ) ,-7) +shuffle((shuffle((transpose(X,-5) +transpose(step(transpose(X,-7) ,12) ,7) ) ) +(arpeggio(X) |(X+transpose(X,4) ) ) ) ) ) ,12) ) +transpose(step(shuffle(((((arpeggio(shuffle(X) ) +step(X,12) ) |shuffle(echo(((X|X) +transpose((X|X) ,7) ) ,4,6) ) ) +transpose(transpose(step(shuffle(transpose(step(X,12) ,-7) ) ,12) ,4) ,7) ) +step((step(arpeggio(transpose((X+transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,7) ) ,4) ) ,12) |step(shuffle(step(X,12) ) ,12) ) ,12) ) ) ,12) ,4) ) +transpose((transpose(echo(transpose(arpeggio(step(transpose(X,-5) ,12) ) ,4) ,4,6) ,4) |arpeggio(step(((((X+transpose((X|X) ,7) ) +transpose(shuffle(X) ,7) ) +transpose(((X|X) |(X|X) ) ,12) ) +transpose(transpose(transpose(transpose(transpose(X,-5) ,4) ,4) ,4) ,12) ) ,12) ) ) ,7) ) ,-5) +(step(transpose(arpeggio((shuffle((arpeggio(X) +transpose(arpeggio(((step(X,12) +transpose(X,4) ) +transpose(((X+transpose(X,4) ) +transpose(X,7) ) ,7) ) ) ,12) ) ) +transpose(shuffle(shuffle((((X|X) |X) +transpose(transpose(X,-5) ,12) ) ) ) ,12) ) ) ,4) ,12) |shuffle(transpose((step(transpose(transpose(X,4) ,-5) ,12) |((X|arpeggio(((X+transpose(X,4) ) +transpose(X,7) ) ) ) |transpose(transpose(X,4) ,4) ) ) ,-5) ) ) ) ,4) ) +transpose(arpeggio(transpose(((arpeggio(transpose(transpose(transpose(shuffle(echo(transpose((transpose(X,4) +X) ,-5) ,4,6) ) ,-5) ,-7) ,-7) ) +transpose(shuffle((arpeggio(step(arpeggio(arpeggio(X) ) ,12) ) +echo(arpeggio((((X|X) +transpose((transpose(X,4) |(X|X) ) ,12) ) +shuffle(X) ) ) ,4,6) ) ) ,7) ) |((transpose((transpose(step(X,12) ,-7) |(shuffle(((X|X) +X) ) |X) ) ,-7) +transpose((shuffle(transpose(arpeggio(((step(X,12) +transpose(arpeggio(X) ,4) ) +transpose((X|X) ,7) ) ) ,4) ) +transpose((arpeggio(transpose(step((X|X) ,12) ,-5) ) |(transpose(step(((X+transpose(X,4) ) +transpose(X,7) ) ,12) ,4) +transpose(shuffle((X|X) ) ,4) ) ) ,7) ) ,12) ) +transpose(transpose(arpeggio(((step(shuffle(shuffle(X) ) ,12) +transpose(((X+transpose(X,7) ) +(X+echo(X,4,6) ) ) ,7) ) +transpose(transpose(arpeggio(shuffle(X) ) ,4) ,12) ) ) ,4) ,7) ) ) ,-7) ) ,7) ) ,-5) +transpose(transpose(shuffle(transpose(transpose(((arpeggio(transpose((X+X) ,4) ) +transpose(echo(X,4,6) ,4) ) +transpose(transpose((transpose((X+transpose(X,12) ) ,-7) +transpose(shuffle(shuffle(X) ) ,7) ) ,4) ,7) ) ,4) ,-7) ) ,-5) ,7) ) ) ,7) ) ,12)
random seed used was 0

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