Editing Coroutine (section)

==Common uses==
Coroutines are useful to implement the following:

* [[State machine]]s within a single subroutine, where the state is determined by the current entry/exit point of the procedure; this can result in more readable code compared to use of [[goto]], and may also be implemented via [[mutual recursion]] with [[tail call]]s.
* [[Actor model]] of concurrency, for instance in [[video game]]s. Each actor has its own procedures (this again logically separates the code), but they voluntarily give up control to central scheduler, which executes them sequentially (this is a form of [[cooperative multitasking]]).
* [[Generator (computer programming)|Generator]]s, and these are useful for [[Stream (computing)|streams]]{{snd}}particularly input/output{{snd}}and for generic traversal of data structures.
* [[Communicating sequential processes]] where each sub-process is a coroutine. Channel inputs/outputs and blocking operations yield coroutines and a scheduler unblocks them on completion events. Alternatively, each sub-process may be the parent of the one following it in the data pipeline (or preceding it, in which case the pattern can be expressed as nested generators).
* Reverse communication, commonly used in mathematical software, wherein a procedure such as a solver, integral evaluator, ... needs the using process to make a computation, such as evaluating an equation or integrand.