ref: 3e1e9621d1f19b221d59191ed55e78b171a5fe93
dir: /TODO/
* Stop comparing strings all the time * Stop copying the entire goal stack into every choicepoint * Stop creating choicepoints when it is not needed * How to implement builtins nicely? * Right now we copy and allocate a lot, but almost never free stuff. * Many builtins should really throw an error, but they just fail for now. * Exceptions (throw, catch) * Modules (I try to do something like SWI prolog for now, but I know there is also an iso standard)