Add more promise methods (RFC 35) #2084
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Theodus
added
the
changelog - added
| @@ -159,6 +160,88 @@ actor Promise[A: Any #share] | |||
| _attach(consume attach) | |||
| promise | |||
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| fun tag add[B: Any #share = A](p: Promise[B]): Promise[(A, B)] => | |||
| """ | |||
| Add two promises into one promise that returns the result of both when | |||
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can i add multiple promises together?
Add a and b together then add that together with c?
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You can, but you would get back a Promise[((A, B), C)].
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I think that probably be documented somewhere.
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Q: @Theodus how is that different than a join?
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join combines multiple promises of the same type and returns their final values in an array where they are in an unknown order. add combines promises that may yield values of different types, but even if they are the same type the promise that each value came from is known based on the order that it appears in the final tuple.
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join : Iterator[Promise[A]] -> Promise[Array[A]]
add : (Promise[A], Promise[B]) -> Promise[(A, B)]There was a problem hiding this comment.
I think it makes sense to update the add and join descriptions to make that clear.
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@Theodus what do you think of adding to the top level Promises documentation examples to have examples of using the new methods? |
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@SeanTAllen I was intending to add an example in the pony patterns for waiting with the timeout and select methods. I don't think it's necessary to add more examples to the top level documentation since it may become a bit overwhelming for new users. |
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@Theodus So the patterns would be on how to accomplish common async joining etc type things with Promises? sounds good. |
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Good to merge once the small doc update above is done. Probably needs an update now that explicit partial call was merged. |
This PR expands the promises API. Closes #1691.