michaelficarra · August 29, 2015 14:07 · Oct 15, 2014 · Oct 15, 2014
diff --git a/monads.js b/monads.js
@@ -1,13 +1,30 @@
-var _Container = function(val) { this.val = val }
-var Container = function(val) { return new _Container(val); }
+function Container(val) {
+  this.val = val
+}
+
+// Functor's `fmap` in Haskell
 Container.prototype.map = function(f) {
   return new Container(f(this.val));
-}
+};
+
+// Monad's `>>=` (pronounced bind) in Haskell
 Container.prototype.flatMap = function(f) {
   return f(this.val);
-}
-var c = new Container(2);
-// functor
-c.map(function(x) { return x+2});
-// monad
-c.flatMap(function(x){ return x+2}).flatMap(function(x) {return x* -1 });
+};
+
+// Monad's `return` in Haskell
+Container.of = function(val) {
+  return new Container(val);
+};
+
+var c = Container.of(2);
+
+c.map(function(x) {
+  return x+2;
+}); // === Container.of(4)
+
+c.flatMap(function(x){
+  return Container.of(x+2);
+}).flatMap(function(x){
+  return Container.of(x * -1);
+}); // === Container.of(-4)
diff --git a/monads.js b/monads.js
@@ -0,0 +1,13 @@
+var _Container = function(val) { this.val = val }
+var Container = function(val) { return new _Container(val); }
+Container.prototype.map = function(f) {
+  return new Container(f(this.val));
+}
+Container.prototype.flatMap = function(f) {
+  return f(this.val);
+}
+var c = new Container(2);
+// functor
+c.map(function(x) { return x+2});
+// monad
+c.flatMap(function(x){ return x+2}).flatMap(function(x) {return x* -1 });