Add async primitives for http queries, failure handling and mapping non-async functions

async.js

@@ -2,6 +2,9 @@ function Async() {
 	return {
 		apply: apply,
 		bind: bind,
+		fail: fail,
+		http: http,
+		map: map,
 		parallel: parallel,
 		run: run,
 		sequence: sequence,
@@ -35,6 +38,20 @@ function Async() {
 		};
 	}
 
+	function fail(message) {
+		return function(f) {
+			console.log(message);
+		}
+	}
+
+	function map(mapper) {
+		return function(x) {
+			return function(f) {
+				f(mapper(x));
+			};
+		};
+	}
+
 	function parallel() {
 		var threads = arguments;
 		var pending = threads.length;
@@ -96,4 +113,19 @@ function Async() {
 		};
 	}
 
+	function http(query) {
+		return function(f) {
+			var xhr = new XMLHttpRequest();
+			xhr.addEventListener('load', function() {
+				f(this);
+			});
+			xhr.open(query.method, query.url);
+			if(query.method == 'POST') {
+				xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
+			}
+			xhr.send(query.body);
+
+		};
+	}
+
 }