Editing Continuation (section)

===Uses===
Continuations simplify and clarify the implementation of several common [[software design pattern|design pattern]]s,  including [[coroutine]]s/[[green thread]]s and [[exception handling]], by providing the basic, low-level primitive which unifies these seemingly unconnected patterns.  Continuations can provide elegant solutions to some difficult high-level problems, like programming a web server that supports multiple pages, accessed by the use of the forward and back buttons and by following links.  The [[Smalltalk]] [[Seaside (software)|Seaside]] web framework uses continuations to great effect, allowing one to program the web server in procedural style, by switching continuations when switching pages.

More complex constructs for which ''"continuations provide an elegant description"''<ref name="history_of_continuations"/> also exist. For example, in [[C (programming language)|C]], [[longjmp]] can be used to jump from the middle of one [[Function (computer science)|function]] to another, provided the second function lies deeper in the stack (if it is waiting for the first function to return, possibly among others). Other more complex examples include [[coroutine]]s in [[Simula|Simula 67]], [[Lua (programming language)|Lua]], and [[Perl]]; tasklets in [[Stackless Python]]; [[Generator (computer science)|generators]] in [[Icon (programming language)#Generators|Icon]] and [[Python (programming language)|Python]]; continuations in [[Scala (programming language)|Scala]] (starting in 2.8); [[Fiber (computer science)|fibers]] in [[Ruby (programming language)|Ruby]] (starting in 1.9.1); the [[backtracking]] mechanism in [[Prolog]]; [[Monad (functional programming)|monads]] in [[functional programming]]; and [[Thread (computer science)|threads]].