What is the etymology of `GenServer.cast`

I think @rvirding would be the one to answer this but I always personally thought of it as “casting into the unknown”. I smiled when I read thar. Possibly with an etymological relationship to “broadcast”?

How I see it:

To cast something, is to throw it (“let him who is without sin cast the first stone”). So you cast a message, you don’t expect a response. You’re just tossing it over like, “Here, catch this.”

To call, like calling a person, (“Hello, Joe”), you expect a response.

Definition of cast

(Entry 1 of 2)
transitive verb

1a : to cause to move or send forth by throwing

Although cast means “to throw,” the traditional usage of cast implies specifically that you are throwing the item with the mentality that the item will never return. This is why people don’t cast baseballs, but they do cast things into the sea, and they do cast off their chains. This is why we have “outcasts,” “castaways,” and other individuals who are presumably gone forever. It’s an excellent choice for the function in question, I think.

These are all great answers! I was so stuck on the data conversion meaning that I didn’t even think about “throwing”. This gives me much relief, thank you!

Edited to add: re-reading this sentence from my original post
“However, cast when referring to “I’m sending out a message yet don’t want a response and don’t even care if it was received”” is now making me all

I honestly wouldn’t read too much into the actual call names. They needed/wanted to label two different interfaces, the completely synchronous and well-checked and the asynchronous unchecked ones.

I am guessing here as I wasn’t on the otp team (I don’t do this high-level stuff but prefer the basics ).

So the basic erlang send is asynchronous and without any guarantees at all: the receiver may or may not be there and the message may or may not arrive. It really is a “send and pray”. There is in fact only guarantee and that is if you send 2 messages and both arrive they will arrive in the same order as you sent them. The gen_server/gen_statem:cast models this exactly, in fact if you look in the code it ends up just doing a raw send. So what do you call this? You could call this send as well but then people could get mixed up between it and underlying message sending. Also some OO system you send for the synchronous object call.

The name call is easier to understand. It has all the guarantees you can get: the receiver is there and alive, you will get a reply within your specified timeout and you will know if the receiver dies before it can reply. This is sort of close to remote function calls so calling it call is pretty good.

In the older now deprecated gen_fsm the calls were called send_event and sync_send_event.

It is interesting to look at the code for the synchronous gen_server:call. Check out the do_call function in the gen.erl module. It shows how easy it actually is to get this reliability. It shows how right we got the primitives

These are just my thoughts.

Now I wonder, as a non native English speaker, why “cast” has been chosen to mean “type conversion of some data”.

I am not native speaker either, I think typecast has special meaning in performing art. Eg: Clint Eastwood is often typecast as a cowboy.

This is a great question with a fun answer! As I’ve heard it, the root of both “to cast” meaning to convert the type, and “to cast” meaning to throw or send is actually from the same context: Pottery. When you form a clay vessel this can be referred to as “throwing” or “casting”. This activity involves both the rapid spinning of the clay which gives us the “throwing” connotation, as well as the idea of giving something a form, which gives us the “typecast” usage.

It’s quite a rabbit hole, actually. Here is a pottery site explaining the use of “throw” in pottery, from the old English “thrawan.” Presumably this led to usage in other contexts, e.g. “cast iron.”

Why is it called Throwing?

Origin of “To throw”: Old Engilish - twist, to turn, to propel.

Some potters describe their work at the potters wheel as turning. The Old English word thrawan from which to throw comes, means to twist or turn. Going back even farther, the Indo-European root *ter- means to rub, rub by twisting, twist, turn. The German word drehen, a direct relative of to throw, means turn and is used in German for throwing. Because the activity of forming pots on the wheel has not changed since Old English times, the word throw has retained its original meaning in the language of pottery but has developed a completely different meaning in everyday usage. Those who say they throw pots are using the historically correct term. Those who say they turn pots are using more current language. Both are saying the same thing.

@rvirding Thanks so much for that detailed explanation! And thank you @benwilson512 and @Dusty for the extra info!