Data streams make preeminent instruments for playing certain classical themes from analysis. Complex networks of processes, e#ortlessly orchestrated by lazy evaluation, can enumerate terms of formal power series ad infinitum. Expressed in a language like Haskell, working programs for power-series operations are tiny gems, because the natural programming style for data streams fits the mathematics so well---often better than time-honored summation notation. The cleverest copyist is the one whose music is performed with the most ease without the performer guessing why. --- Jean Jacques Rousseau, Dictionary of Music 1 Overture Like persistent folk tunes, the themes I intend to play here have been arranged for various ensembles over many years. Some performances have been angular, and some melodic, but all share the staying power of good music. The themes stick in mind, to be enjoyed again and again as each performance exposes new surfaces and depths. My subject is "power-stream compositio...