Pedagogical algorithm visualization systems produce graphical representations that aim to assist learners in understanding the dynamic behavior of computer algorithms. In order to foster active learning, educators have explored algorithm visualization systems that empower learners to construct their own visualizations of algorithms under study. Notably, these systems support a similar development model in which coding the algorithm is temporally distinct from viewing and interacting with the resulting visualization. To explore the benefits of narrowing the gap between coding an algorithm and viewing its visualization, we have implemented "What You See Is What You Code," a novel, "radically dynamic" development model to facilitate learner-constructed algorithm visualizations. In this model, the line of algorithm code currently being edited is reevaluated on every edit, leading to the dynamic update of an accompanying visualization of the algorithm. Analysis of usability studies involving introductory computer science students suggests that the immediacy of the model?s feedback can help novices to quickly identify and correct programming errors, and ultimately to understand their code?s execution.