
History of Actors - tonyg
https://eighty-twenty.org/2016/10/18/actors-hopl
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gradschool
The Pony language uses actors and has some other cool features, worth checking
out if this subject interests you.

[http://www.ponylang.org/](http://www.ponylang.org/)

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burnbabyburn
I recall Carl Hewitt talking about everything being an actor, even messages,
and implementations differing from this idea, am I wrong?

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abecedarius
You can think of a pure-data object, such as a message, as a special kind of
actor whose protocol includes messages to extract the parts. It gets tricky
when it comes to comparisons: you want e.g. a boolean to be able to say "yes,
I'm equal to this boolean b you sent me" but you also want to be able to send
a transparent forwarder b' that wraps a "real" boolean b. I'm not sure how the
different actor languages dealt with these issues.

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tonyg
Exactly. Data is necessary to make control flow decisions; the purely
behavioural approach suffers infinite regress without some form of concrete
data.

I suspect that this problem was one of the reasons later actor languages came
to include some kind of data; in the case of Erlang, messages are the data,
compared structurally; in E, object identities can be compared without sending
messages to the objects.

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alblue
Surprised this didn't make any mention of Hoare's Communicating Sequential
Processes, which laid a lot of the groundwork for concurrent message passing.

[https://en.m.wikipedia.org/wiki/Communicating_sequential_pro...](https://en.m.wikipedia.org/wiki/Communicating_sequential_processes)

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tonyg
You're right that CSP has been influential more generally, but it doesn't
relate directly enough to the history of the actor model, which is the focus
here. (Though you can see, in the first paper specifically about CSP from
1978, citations to earlier actor-model work, and of course all the researchers
involved had been following each other's work closely for years; a great
amount of feedback was taking place continuously.)

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intrasight
A three-point history of actors

1\. In the 500s BC, a poet named Thespis is credited with innovating a new
style in which a solo actor performed the speeches of the characters in the
narrative.

2\. In 471 BC, the dramatist Aeschylus innovated a second actor, thus making
dialogue between characters possible onstage.

3\. Around 468 BC, Sophocles introduced a third actor making more complex
dramatic situations possible. Three actors subsequently became the formal
convention.

from
[http://www.crystalinks.com/greektheater.html](http://www.crystalinks.com/greektheater.html)

