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# init(_:)

Creates a publisher that invokes a promise closure when the publisher emits an element.

```
init(_ attemptToFulfill: @escaping (@escaping Future<Output, Failure>.Promise) -> Void)
```

## Parameters

`attemptToFulfill`

A [`Future.Promise`](/documentation/Combine/Future/Promise) that the publisher invokes when the publisher emits an element or terminates with an error.

---

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