Add a Cache module compatible with the Async monad

cache.js

@@ -0,0 +1,54 @@
+function Cache() {
+	function Cache(loader) {
+		this.loader = loader;
+		this.loaded = {};
+		this.loading = {};
+	}
+
+	Cache.prototype.get = function(key) {
+		return function(f) {
+			if(this.loaded[key] != undefined) {
+				f(this.loaded[key]);
+			} else {
+				this.startLoading(key);
+				this.loading[key].push(f);
+				this.loader(key)(this.store(key));
+			}
+		}.bind(this);
+	};
+
+	Cache.prototype.warmUp = function(key) {
+		if(this.loaded[key] == undefined) {
+			this.startLoading(key);
+			this.loader(key)(this.store(key));
+		}
+	};
+
+	Cache.prototype.startLoading = function(key) {
+		if(this.loading[key] == undefined) {
+			this.loading[key] = [];
+		}
+	};
+
+	Cache.prototype.store = function(key) {
+		return function(value) {
+			this.loaded[key] = value;
+			for(var i = 0; i < this.loading[key].length; i++) {
+				this.loading[key][i](value);
+			}
+			this.loading[key] = null;
+		}.bind(this);
+	};
+
+	return {
+		make: make
+	};
+
+	function make(loader) {
+		var cache = new Cache(loader);
+		return {
+			get: cache.get.bind(cache),
+			warmUp: cache.warmUp.bind(cache)
+		};
+	}
+}