Actually, it does work for interaction if you program interactions Pyret-style, which effectively separate model from view. Models are updated functionally, so

Actually, it does work for interaction if you program interactions Pyret-style, which effectively separate model from view. Models are updated functionally, so it's trivial to write tests for the model-updaters. Animations and games are obtained by having the underlying event loop infrastructure automatically compose these functions. This is the same methodology we use in Racket and in the Bootstrap curriculum [http://www.bootstrapworld.org/ http://www.bootstrapworld.org/].