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    <p><strong>A trivial example of using continuation</strong> would be implementing a thread (fiber if you wish) manager on a single-processor machine. The scheduler would interrupt the execution flow periodically (or, in the case of fibers, be invoked at various strategic points in the code), save the <em>continuation state</em> (corresponding to the <em>current thread</em>), then switch to a different <em>continuation state</em> (corresponding to a different thread whose state was saved previously.)</p> <p>Referring to your assembly background, <strong>the continuation state would capture such details as instruction pointer, registers, and stack context (pointer)</strong>, to be saved and restored at will.</p> <p>Another way of using continuation would be to <strong>think of replacing method calls with several thread-like entities</strong> that co-exist in parallel (either running or suspended) passing control to each other using continuation contexts instead of the 'classic' <code>call</code> paradigm. They would operate on global (shared) data instead of relying on parameters. This is to some extent more flexible than <code>call</code> in the sense that stack does not have to wind up then down (<code>calls</code> are <em>nested</em>), but control can pass around arbitrarily.</p> <p><strong>Attempting to visualize this concept</strong> in a language such a C, imagine having one big loop with a single <code>switch(continuation_point) { case point1: ... }</code> statement, where each <code>case</code> corresponds to a continuation-savepoint, and where the code inside each <code>case</code> can alter the value of <code>continuation_point</code> and relinquish control to that <code>continuation_point</code> by <code>break</code>ing from the <code>switch</code> and engaging the next iteration in the loop.</p> <p>What is the context of your question? Any particular scenarios you are interested in? Any particular programming language? Is the thread/fibre example above sufficient?</p>
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    1. POWhat is call/cc?
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    1. USTim Cooper
    1. USvladr
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    1. COThanks Vlad, if I understood you correctly, continuations are some kind of GOTO with state persistence. I just don't get why would I want to use it. There is no context, I'm just looking for right context for it. (Bumped into cont and call/cc while browsing randomly).
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      1. USMichał Rudnicki
    2. COCorrect; see my while(true) { switch(continuation_point) { } } example (switch/case is one way to structure GOTO semantics, continuations are yet another variation.)
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    3. COOf course, call/cc as a concept has the advantage that it is tangible and can be passed around. Also, in the simplified while/switch example the only state captured was 'continuation_point', whereas with call/cc you capture the stack too
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