TCO is a great feature if you want to compile to a language. Recursion is the mother of all loops. TCO really only applies if you have things tail called, and l

TCO is a great feature if you want to compile to a language. Recursion is the mother of all loops. TCO really only applies if you have things tail called, and long string of optimizable tail calls are rare. I have debugged poorly written defmacros for longer time than I spent fighting macro hygiene. I implemented defmacro using syntax rules (about 7 lines of code if you have access to schemes with optional and keyword arguments) and use it frequently. My rule is however that if I ever want to introduce bindings of any kind I will use defmacro. Simple. Saves me a lot of pain. But when it comes to macros there is no truth. This discussion has been going on long enough for most o us to know that it is a matter of taste. Call/cc is overkill. It is a shitty, leaky abstraction that nobody really wants. Delimited continuations are the bee's knees! They compose, capture just the things you tell it to and are fast. They follow the idea of having a well chosen set of primitives as building blocks. You want CL's tagbody? No problem. Fast coroutine style generators? You got it. Cooperative, fiber based multitasking? Just a pure scheme library waiting to be used!