I've programmed in Scheme on and off over the last decade or so. callcc comes in handy for "return" or "break" functionality. More sophisticated uses, like thre

I've programmed in Scheme on and off over the last decade or so. callcc comes in handy for "return" or "break" functionality. More sophisticated uses, like threading or coroutines, have been around for a long time. Obviously those operations are harder to implement but they do exist and are widely used.