The self-assembly of computer code fragments into functional programs is a non-trivial process, which would aid software evolution if achievable, and may provide insights into mechanisms of molecular information processing. Uwe Tangen has focussed on the control loop structures (such as the while loop) available at microcontroller levels and above and investigated self-assembling composition of components which represent individual sequential or loop structures. The resulting simulations build a bridge between the GenSA level of circuit self-assembly, the more general pattern matching processing of classifier systems and the conventional carriers of modern information processing.