We present an algorithmic composition system designed to be accessible to those with minimal programming skills and little musical training, while at the same time allowing the manipulation of detailed musical structures more rapidly and more fluidly than would normally be possible for such a user group. These requirements led us to devise non- standard programming abstractions as the basis for a novel graphical music programming language in which a single basic element permits indeterminism, parallelism, choice, multi-choice, recursion, weighting and looping. The system has general musical expressivity, but for simplicity here we focus on manipulating samples. The musical abstractions behind the system have been implemented as a set of SuperCollider classes to enable end-user testing of the graphical programming language via a Wizard of Oz prototyping methodology. The system is currently being tested with undergraduate Music Technology students who are typically neither programmers, nor traditional musicians
