> A different programming paradigm, for instance, would be the use of delimited continuations such that the API you invoke suspends the current call stack, exec

> A different programming paradigm, for instance, would be the use of delimited continuations such that the API you invoke suspends the current call stack, executes the I/O operation, then resume the call stack with the result of the I/O operation. guile has recently gotten guile-fibers which works like this. It is really an amazing way to do concurrency.