Breeding Faster Turtles: Progress towards a Netlogo Compiler

Despite the stereotype concerning their biological counterparts, NetLogo's turtles are fast. NetLogo (Wilensky 1999a) contains a sophisticated interpreter that has been highly optimized. Nevertheless, NetLogo turtles aren't as fast as they could be. Interpretation necessarily incurs a performance penalty. Thus, we are in the process of replacing NetLogo's interpreter with a compiler. This transition is happening in phases. In this paper, we discuss the architecture of NetLogo's interpreter and explain the first phase of the transition to compilation, which uses inlining to generate efficient bytecode from abstract syntax trees. This technique measurably reduces the interpreter overhead, while permitting a gradual transition to a compiled architecture. We approach the task of compiler design from the perspective of a powerful agent based modeling language with “low threshold” design goals. Preliminary benchmark results are presented, in addition to a forecast of further steps towards a full NetLogo compiler.