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| // This is in response to https://gist.github.com/Peeja/5284697. | |
| // Peeja wanted to know how to convert some callback-based code to functional | |
| // style using promises. | |
| var Promise = require('rsvp').Promise; | |
| var ids = [1,2,3,4,5,6]; | |
| // If this were synchronous, we'd simply write: | |
| // getTweet :: ID -> Tweet | |
| var getTweet = function(id) { return 'Tweet text ' + id }; | |
| // upcase :: Tweet -> String | |
| var upcase = function(tweet) { return tweet.toUpperCase() }; | |
| var rotten = ids.map(function(id) { | |
| return upcase(getTweet(id)); | |
| }); | |
| // Or, to put it in the form of a pipeline with two map calls: | |
| var rotten = ids.map(getTweet).map(upcase); | |
| console.log(rotten); | |
| // How about we simply use promised decorator instead of introducing | |
| // more and more promise spicific util functions. That way one can | |
| // just decorate existing sync code and that's it! | |
| var getTweet = function(id) { | |
| var promise = new Promise(); | |
| setTimeout(function() { promise.resolve('Tweet text ' + id) }, 500); | |
| return promise; | |
| }; | |
| // just decorate our sync function | |
| var upcase = promised(function(tweet) { return tweet.toUpperCase() }); | |
| // keep the rest same | |
| var rotten = ids.map(getTweet).map(upcase); | |
| // make async logger :) | |
| var print = promised(console.log); | |
| // print all the values | |
| print.apply(0, rotten); | |
| // For details on `promised` see: | |
| // https://github.com/Gozala/micro-promise/blob/master/core.js#L194-L217 | |
| // I also have written more detailed post about this | |
| // a while ago: | |
| // http://jeditoolkit.com/2012/04/26/code-logic-not-mechanics.html#post |
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