Promises (first look)

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Small fixes

vendors/Q/examples/async-generators/4-flow-control.js

@@ -0,0 +1,42 @@
+"use strict";
+
+var Q = require("../../q");
+
+// We get back blocking semantics: can use promises with `if`, `while`, `for`,
+// etc.
+var filter = Q.async(function* (promises, test) {
+    var results = [];
+    for (var i = 0; i < promises.length; i++) {
+        var val = yield promises[i];
+        if (test(val)) {
+            results.push(val);
+        }
+    }
+    return results;
+});
+
+var promises = [
+    Q.delay("a", 500),
+    Q.delay("d", 1000),
+    Q("l")
+];
+
+filter(promises, function (letter) {
+    return "f" > letter;
+}).done(function (all) {
+    console.log(all); // [ "a", "d" ]
+});
+
+
+// we can use try and catch to handle rejected promises
+var logRejections = Q.async(function* (work) {
+    try {
+        yield work;
+        console.log("Never end up here");
+    } catch (e) {
+        console.log("Caught:", e.message);
+    }
+});
+
+var rejection = Q.reject(new Error("Oh dear"));
+logRejections(rejection); // Caught: Oh dear