<p><pre><code>   Continuations are easy: functions are hard.
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That&#x27;s a deep truth. Thinking about of computation message-passing actors is Hewitt&#x27;s and Milner&#x27;s dream. It&#x27;s a hard sell to the programming mainstream though. In particular the functional programming community sees functions as the basis on top of which everything else needs to be layered as an effect. It&#x27;s much more productive to go the other way round and see functions as a very peculiar and well-behaved from of message exchange. (Scala also makes this point.)