https://github.com/jamesmacaulay/cljs-promises

A ClojureScript library for using JS promises with core.async
https://github.com/jamesmacaulay/cljs-promises

Last synced: 24 days ago
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A ClojureScript library for using JS promises with core.async

• Host: GitHub
• URL: https://github.com/jamesmacaulay/cljs-promises
• Owner: jamesmacaulay
• License: mit
• Created: 2014-04-03T03:28:21.000Z (over 10 years ago)
• Default Branch: master
• Last Pushed: 2016-11-15T06:53:21.000Z (about 8 years ago)
• Last Synced: 2024-09-12T22:51:01.181Z (2 months ago)
• Language: Clojure
• Size: 172 KB
• Stars: 90
• Watchers: 6
• Forks: 6
• Open Issues: 2
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# cljs-promises

A ClojureScript library for working with JavaScript promises.

### Overview

This library leverages the power of [core.async](https://github.com/clojure/core.async) to let you write promise code like this:

```clojure

(cljs-promises.async/extend-promises-as-pair-channels!)

(go

 (let [user-promise (get-user "jamesmacaulay")]

   (try

     (println (:blog ( user-promise)))

     (catch js/Error e

       (println (str "Could't get user data: " (ex-message e))))))

```

The first line globally extends `Promise` instances to act like **read-only channels** which, once resolved, **endlessly produce the same value or error to anyone who takes from them**. Because promises have built-in error semantics which don't have any direct corollary in core.async, there are different ways that we can represent promise results. In this example we've extended promises in a way that values taken from them with core.async are actually `[value error]` pairs, where you get `[value nil]` from a fulfilled promise and `[nil error]` from a rejected promise.

`` is a macro provided by `cljs-promises.async` which takes one of these pairs from a promise with core.async's `