This kind of stateless programming is a great fit for visual graph UIs. A lot of visual effects and game programming tools offer some kind of node-based environ

This kind of stateless programming is a great fit for visual graph UIs. A lot of visual effects and game programming tools offer some kind of node-based environment for this reason. The algorithms can even appear more intuitive when you remove the linear text trappings of traditional programming languages, because you can see at a glance which nodes are the changing input values and which are the dependent operations. (To a point — once the graphs get too big to comfortably fit on the screen, the clarity advantage starts to disappear. At that point you'd better hope the tool offers some kind of grouping/nesting functionality to manage the growing complexity.) Node UIs can also offer immediate visual feedback on intermediate states, which makes it easier to tweak the algorithm compared to traditional debugging.