diff --git a/README.md b/README.md
index ef5f370..8a53059 100644
--- a/README.md
+++ b/README.md
@@ -38,7 +38,8 @@ Dual license notice: The default license for this project is GPL 3.0. However, i
   - [jQuery UI](https://jqueryui.com/)
   - [github.com/kamranahmedse/jquery-toast-plugin](https://github.com/kamranahmedse/jquery-toast-plugin)
   - [github.com/hiddentao/squel](https://github.com/hiddentao/squel)
-  - [github.com/BorisMoore/jsrender](https://github.com/BorisMoore/jsrender)
+  - [github.com/BorisMoore/jsrender](https://github.com/BorisMoore/jsrender) - Templating engine
+  - [github.com/mihaifm/linq](https://github.com/mihaifm/linq) - LINQ for JavaScript
 - [Includes binaries](https://github.com/gnh1201/welsonjs/blob/master/bin/README.MD)
 - [module.exports](https://nodejs.org/en/knowledge/getting-started/what-is-require/), CommonJS, UMD compatibility
 - [NPM](https://www.npmjs.com/) compatibility
diff --git a/app.js b/app.js
index a33aed6..7be0f5e 100644
--- a/app.js
+++ b/app.js
@@ -560,6 +560,9 @@ var is = require("app/assets/js/is-0.9.0.min");
 //var Intl = require("app/assets/js/Intl-1.2.5-e93b114.min");
 //console.log(new Intl.NumberFormat().format(1234567890.123456));
 
+// linq.js - LINQ for JavaScript
+var Enumerable = require("app/assets/js/linq-4.0.2.wsh.js")._default;
+
 // Dive into entrypoint 
 function __main__() {
     console.log("");
diff --git a/app/assets/js/linq-4.0.2.wsh.js b/app/assets/js/linq-4.0.2.wsh.js
new file mode 100644
index 0000000..92855cf
--- /dev/null
+++ b/app/assets/js/linq-4.0.2.wsh.js
@@ -0,0 +1,3070 @@
+/*--------------------------------------------------------------------------
+ * linq.js - LINQ for JavaScript
+ * licensed under MIT License
+ *------------------------------------------------------------------------*/
+
+var Functions = {
+    Identity: function (x) { return x; },
+    True: function () { return true; },
+    Blank: function () { }
+};
+
+var Types = {
+    Boolean: typeof true,
+    Number: typeof 0,
+    String: typeof "",
+    Object: typeof {},
+    Undefined: typeof undefined,
+    Function: typeof function () { }
+};
+
+var funcCache = { "": Functions.Identity };
+
+var Utils = {
+    createLambda: function (expression) {
+        if (expression == null) return Functions.Identity;
+        if (typeof expression === Types.String) {
+            // get from cache
+            var f = funcCache[expression];
+            if (f != null) {
+                return f;
+            }
+
+            if (expression.indexOf("=>") === -1) {
+                var regexp = new RegExp("[$]+", "g");
+
+                var maxLength = 0;
+                var match;
+                while ((match = regexp.exec(expression)) != null) {
+                    if (match[0].length > maxLength) {
+                        maxLength = match[0].length;
+                    }
+                }
+
+                var argArray = [];
+                for (var i = 1; i <= maxLength; i++) {
+                    var dollar = "";
+                    for (var j = 0; j < i; j++) {
+                        dollar += "$";
+                    }
+                    argArray.push(dollar);
+                }
+
+                var args = argArray.join(",");
+
+                f = new Function(args, "return " + expression);
+                funcCache[expression] = f;
+                return f;
+            }
+            else {
+                var expr = expression.match(/^[(\s]*([^()]*?)[)\s]*=>(.*)/);
+                f = new Function(expr[1], (expr[2].match(/\breturn\b/) ? expr[2] : "return " + expr[2]));
+                funcCache[expression] = f;
+                return f;
+            }
+        }
+        return expression;
+    },
+
+    defineProperty: function (target, methodName, value) {
+        Object.defineProperty(target, methodName, {
+            enumerable: false,
+            configurable: true,
+            writable: true,
+            value: value
+        })
+    },
+
+    compare: function (a, b) {
+        return (a === b) ? 0 : (a > b) ? 1 : -1;
+    },
+
+    dispose: function (obj) {
+        if (obj != null) obj.dispose();
+    },
+
+    hasNativeIteratorSupport: function () {
+        return typeof Symbol !== 'undefined' && typeof Symbol.iterator !== 'undefined';
+    }
+};
+
+var State = { Before: 0, Running: 1, After: 2 };
+
+var IEnumerator = function (initialize, tryGetNext, dispose) {
+    var yielder = new Yielder();
+    var state = State.Before;
+
+    this.current = yielder.current;
+
+    this.moveNext = function () {
+        try {
+            switch (state) {
+                case State.Before:
+                    state = State.Running;
+                    initialize();
+                // fall through
+
+                case State.Running:
+                    if (tryGetNext.apply(yielder)) {
+                        return true;
+                    }
+                    else {
+                        this.dispose();
+                        return false;
+                    }
+                // fall through
+
+                case State.After:
+                    return false;
+            }
+        }
+        catch (e) {
+            this.dispose();
+            throw e;
+        }
+    };
+
+    this.dispose = function () {
+        if (state != State.Running) return;
+
+        try {
+            dispose();
+        }
+        finally {
+            state = State.After;
+        }
+    };
+};
+
+// tryGetNext yielder
+var Yielder = function () {
+    var current = null;
+    this.current = function () { return current; };
+    this.yieldReturn = function (value) {
+        current = value;
+        return true;
+    };
+    this.yieldBreak = function () {
+        return false;
+    };
+};
+
+// Enumerable constuctor
+var Enumerable = function (getEnumerator) {
+    this.getEnumerator = getEnumerator;
+};
+
+///////////////////
+// Utility Methods
+
+Enumerable.Utils = {};
+
+Enumerable.Utils.createLambda = function (expression) {
+    return Utils.createLambda(expression);
+};
+
+Enumerable.Utils.createEnumerable = function (getEnumerator) {
+    return new Enumerable(getEnumerator);
+};
+
+Enumerable.Utils.createEnumerator = function (initialize, tryGetNext, dispose) {
+    return new IEnumerator(initialize, tryGetNext, dispose);
+};
+
+Enumerable.Utils.extendTo = function (type) {
+    var typeProto = type.prototype;
+    var enumerableProto;
+
+    if (type === Array) {
+        enumerableProto = ArrayEnumerable.prototype;
+        Utils.defineProperty(typeProto, "getSource", function () {
+            return this;
+        });
+    }
+    else {
+        enumerableProto = Enumerable.prototype;
+        Utils.defineProperty(typeProto, "getEnumerator", function () {
+            return Enumerable.from(this).getEnumerator();
+        });
+    }
+
+    for (var methodName in enumerableProto) {
+        var func = enumerableProto[methodName];
+
+        // already extended
+        if (typeProto[methodName] == func) continue;
+
+        // already defined(example Array#reverse/join/forEach...)
+        if (typeProto[methodName] != null) {
+            methodName = methodName + "ByLinq";
+            if (typeProto[methodName] == func) continue; // recheck
+        }
+
+        if (func instanceof Function) {
+            Utils.defineProperty(typeProto, methodName, func);
+        }
+    }
+};
+
+Enumerable.Utils.recallFrom = function (type) {
+    var typeProto = type.prototype;
+    var enumerableProto;
+
+    if (type === Array) {
+        enumerableProto = ArrayEnumerable.prototype;
+        delete typeProto.getSource;
+    }
+    else {
+        enumerableProto = Enumerable.prototype;
+        delete typeProto.getEnumerator;
+    }
+
+    for (var methodName in enumerableProto) {
+        var func = enumerableProto[methodName];
+
+        if (typeProto[methodName + 'ByLinq']) {
+            delete typeProto[methodName + 'ByLinq'];
+        }
+        else if (typeProto[methodName] == func && func instanceof Function) {
+            delete typeProto[methodName];
+        }
+    }
+};
+
+//////////////
+// Generators
+
+Enumerable.choice = function () {
+    var args = arguments;
+
+    return new Enumerable(function () {
+        return new IEnumerator(
+            function () {
+                args = (args[0] instanceof Array) ? args[0]
+                    : (args[0].getEnumerator != null) ? args[0].toArray()
+                        : args;
+            },
+            function () {
+                return this.yieldReturn(args[Math.floor(Math.random() * args.length)]);
+            },
+            Functions.Blank);
+    });
+};
+
+Enumerable.cycle = function () {
+    var args = arguments;
+
+    return new Enumerable(function () {
+        var index = 0;
+        return new IEnumerator(
+            function () {
+                args = (args[0] instanceof Array) ? args[0]
+                    : (args[0].getEnumerator != null) ? args[0].toArray()
+                        : args;
+            },
+            function () {
+                if (index >= args.length) index = 0;
+                return this.yieldReturn(args[index++]);
+            },
+            Functions.Blank);
+    });
+};
+
+Enumerable.empty = function () {
+    return new Enumerable(function () {
+        return new IEnumerator(
+            Functions.Blank,
+            function () { return false; },
+            Functions.Blank);
+    });
+};
+
+Enumerable.from = function (obj) {
+    if (obj == null) {
+        return Enumerable.empty();
+    }
+    if (obj instanceof Enumerable) {
+        return obj;
+    }
+    if (typeof obj == Types.Number || typeof obj == Types.Boolean) {
+        return Enumerable.repeat(obj, 1);
+    }
+    if (typeof obj == Types.String) {
+        return new Enumerable(function () {
+            var index = 0;
+            return new IEnumerator(
+                Functions.Blank,
+                function () {
+                    return (index < obj.length) ? this.yieldReturn(obj.charAt(index++)) : false;
+                },
+                Functions.Blank);
+        });
+    }
+    if (typeof obj == Types.Function && Object.keys(obj).length == 0) {
+        return new Enumerable(function () {
+            var orig;
+
+            return new IEnumerator(
+                function () {
+                    orig = obj()[Symbol.iterator]();
+                },
+                function () {
+                    var next = orig.next();
+                    return (next.done ? false : (this.yieldReturn(next.value)));
+                },
+                Functions.Blank);
+        });
+    }
+
+    if (typeof obj != Types.Function) {
+        // array or array-like object
+        if (typeof obj.length == Types.Number) {
+            return new ArrayEnumerable(obj);
+        }
+
+        // iterable object
+        if (typeof Symbol !== 'undefined' && typeof obj[Symbol.iterator] !== 'undefined') {
+            return new Enumerable(function () {
+                return new IEnumerator(
+                    Functions.Blank,
+                    function () {
+                        var next = obj.next();
+                        return (next.done ? false : (this.yieldReturn(next.value)));
+                    },
+                    Functions.Blank);
+            });
+        }
+    }
+
+    // case function/object: create keyValuePair[]
+    return new Enumerable(function () {
+        var array = [];
+        var index = 0;
+
+        return new IEnumerator(
+            function () {
+                for (var key in obj) {
+                    var value = obj[key];
+                    if (!(value instanceof Function) && Object.prototype.hasOwnProperty.call(obj, key)) {
+                        array.push({ key: key, value: value });
+                    }
+                }
+            },
+            function () {
+                return (index < array.length)
+                    ? this.yieldReturn(array[index++])
+                    : false;
+            },
+            Functions.Blank);
+    });
+},
+
+    Enumerable.make = function (element) {
+        return Enumerable.repeat(element, 1);
+    };
+
+// Overload:function(input, pattern)
+// Overload:function(input, pattern, flags)
+Enumerable.matches = function (input, pattern, flags) {
+    if (flags == null) flags = "";
+
+    if (pattern instanceof RegExp) {
+        flags += (pattern.ignoreCase) ? "i" : "";
+        flags += (pattern.multiline) ? "m" : "";
+        pattern = pattern.source;
+    }
+    if (flags.indexOf("g") === -1) flags += "g";
+
+    return new Enumerable(function () {
+        var regex;
+        return new IEnumerator(
+            function () { regex = new RegExp(pattern, flags); },
+            function () {
+                var match = regex.exec(input);
+                return (match) ? this.yieldReturn(match) : false;
+            },
+            Functions.Blank);
+    });
+};
+
+// Overload:function(start, count)
+// Overload:function(start, count, step)
+Enumerable.range = function (start, count, step) {
+    if (step == null) step = 1;
+
+    return new Enumerable(function () {
+        var value;
+        var index = 0;
+
+        return new IEnumerator(
+            function () { value = start - step; },
+            function () {
+                return (index++ < count)
+                    ? this.yieldReturn(value += step)
+                    : this.yieldBreak();
+            },
+            Functions.Blank);
+    });
+};
+
+// Overload:function(start, count)
+// Overload:function(start, count, step)
+Enumerable.rangeDown = function (start, count, step) {
+    if (step == null) step = 1;
+
+    return new Enumerable(function () {
+        var value;
+        var index = 0;
+
+        return new IEnumerator(
+            function () { value = start + step; },
+            function () {
+                return (index++ < count)
+                    ? this.yieldReturn(value -= step)
+                    : this.yieldBreak();
+            },
+            Functions.Blank);
+    });
+};
+
+// Overload:function(start, to)
+// Overload:function(start, to, step)
+Enumerable.rangeTo = function (start, to, step) {
+    if (step == null) step = 1;
+
+    if (start < to) {
+        return new Enumerable(function () {
+            var value;
+
+            return new IEnumerator(
+                function () { value = start - step; },
+                function () {
+                    var next = value += step;
+                    return (next <= to)
+                        ? this.yieldReturn(next)
+                        : this.yieldBreak();
+                },
+                Functions.Blank);
+        });
+    }
+    else {
+        return new Enumerable(function () {
+            var value;
+
+            return new IEnumerator(
+                function () { value = start + step; },
+                function () {
+                    var next = value -= step;
+                    return (next >= to)
+                        ? this.yieldReturn(next)
+                        : this.yieldBreak();
+                },
+                Functions.Blank);
+        });
+    }
+};
+
+// Overload:function(element)
+// Overload:function(element, count)
+Enumerable.repeat = function (element, count) {
+    if (count != null)
+        return Enumerable.repeat(element).take(count);
+
+    return new Enumerable(function () {
+        return new IEnumerator(
+            Functions.Blank,
+            function () { return this.yieldReturn(element); },
+            Functions.Blank);
+    });
+};
+
+Enumerable.repeatWithFinalize = function (initializer, finalizer) {
+    initializer = Utils.createLambda(initializer);
+    finalizer = Utils.createLambda(finalizer);
+
+    return new Enumerable(function () {
+        var element;
+        return new IEnumerator(
+            function () { element = initializer(); },
+            function () { return this.yieldReturn(element); },
+            function () {
+                if (element != null) {
+                    finalizer(element);
+                    element = null;
+                }
+            });
+    });
+};
+
+// Overload:function(func)
+// Overload:function(func, count)
+Enumerable.generate = function (func, count) {
+    if (count != null)
+        return Enumerable.generate(func).take(count);
+
+    func = Utils.createLambda(func);
+
+    return new Enumerable(function () {
+        return new IEnumerator(
+            Functions.Blank,
+            function () { return this.yieldReturn(func()); },
+            Functions.Blank);
+    });
+};
+
+// Overload:function()
+// Overload:function(start)
+// Overload:function(start, step)
+Enumerable.toInfinity = function (start, step) {
+    if (start == null) start = 0;
+    if (step == null) step = 1;
+
+    return new Enumerable(function () {
+        var value;
+        return new IEnumerator(
+            function () { value = start - step; },
+            function () { return this.yieldReturn(value += step); },
+            Functions.Blank);
+    });
+};
+
+// Overload:function()
+// Overload:function(start)
+// Overload:function(start, step)
+Enumerable.toNegativeInfinity = function (start, step) {
+    if (start == null) start = 0;
+    if (step == null) step = 1;
+
+    return new Enumerable(function () {
+        var value;
+        return new IEnumerator(
+            function () { value = start + step; },
+            function () { return this.yieldReturn(value -= step); },
+            Functions.Blank);
+    });
+};
+
+Enumerable.unfold = function (seed, func) {
+    func = Utils.createLambda(func);
+
+    return new Enumerable(function () {
+        var isFirst = true;
+        var value;
+        return new IEnumerator(
+            Functions.Blank,
+            function () {
+                if (isFirst) {
+                    isFirst = false;
+                    value = seed;
+                    return this.yieldReturn(value);
+                }
+                value = func(value);
+                return this.yieldReturn(value);
+            },
+            Functions.Blank);
+    });
+};
+
+Enumerable.defer = function (enumerableFactory) {
+    return new Enumerable(function () {
+        var enumerator;
+
+        return new IEnumerator(
+            function () { enumerator = Enumerable.from(enumerableFactory()).getEnumerator(); },
+            function () {
+                return (enumerator.moveNext())
+                    ? this.yieldReturn(enumerator.current())
+                    : this.yieldBreak();
+            },
+            function () {
+                Utils.dispose(enumerator);
+            });
+    });
+};
+
+/////////////////////
+// Extension Methods
+
+////////////////////////////////////
+// Projection and Filtering Methods
+
+// Overload:function(func)
+// Overload:function(func, resultSelector<element>)
+// Overload:function(func, resultSelector<element, nestLevel>)
+Enumerable.prototype.traverseBreadthFirst = function (func, resultSelector) {
+    var source = this;
+    func = Utils.createLambda(func);
+    resultSelector = Utils.createLambda(resultSelector);
+
+    return new Enumerable(function () {
+        var enumerator;
+        var nestLevel = 0;
+        var buffer = [];
+
+        return new IEnumerator(
+            function () { enumerator = source.getEnumerator(); },
+            function () {
+                while (true) {
+                    if (enumerator.moveNext()) {
+                        buffer.push(enumerator.current());
+                        return this.yieldReturn(resultSelector(enumerator.current(), nestLevel));
+                    }
+
+                    var next = Enumerable.from(buffer).selectMany(function (x) { return func(x); });
+                    if (!next.any()) {
+                        return false;
+                    }
+                    else {
+                        nestLevel++;
+                        buffer = [];
+                        Utils.dispose(enumerator);
+                        enumerator = next.getEnumerator();
+                    }
+                }
+            },
+            function () { Utils.dispose(enumerator); });
+    });
+};
+
+// Overload:function(func)
+// Overload:function(func, resultSelector<element>)
+// Overload:function(func, resultSelector<element, nestLevel>)
+Enumerable.prototype.traverseDepthFirst = function (func, resultSelector) {
+    var source = this;
+    func = Utils.createLambda(func);
+    resultSelector = Utils.createLambda(resultSelector);
+
+    return new Enumerable(function () {
+        var enumeratorStack = [];
+        var enumerator;
+
+        return new IEnumerator(
+            function () { enumerator = source.getEnumerator(); },
+            function () {
+                while (true) {
+                    if (enumerator.moveNext()) {
+                        var value = resultSelector(enumerator.current(), enumeratorStack.length);
+                        enumeratorStack.push(enumerator);
+                        enumerator = Enumerable.from(func(enumerator.current())).getEnumerator();
+                        return this.yieldReturn(value);
+                    }
+
+                    if (enumeratorStack.length <= 0) return false;
+                    Utils.dispose(enumerator);
+                    enumerator = enumeratorStack.pop();
+                }
+            },
+            function () {
+                try {
+                    Utils.dispose(enumerator);
+                }
+                finally {
+                    Enumerable.from(enumeratorStack).forEach(function (s) { s.dispose(); });
+                }
+            });
+    });
+};
+
+Enumerable.prototype.flatten = function () {
+    var source = this;
+
+    return new Enumerable(function () {
+        var enumerator;
+        var middleEnumerator = null;
+
+        return new IEnumerator(
+            function () { enumerator = source.getEnumerator(); },
+            function () {
+                while (true) {
+                    if (middleEnumerator != null) {
+                        if (middleEnumerator.moveNext()) {
+                            return this.yieldReturn(middleEnumerator.current());
+                        }
+                        else {
+                            middleEnumerator = null;
+                        }
+                    }
+
+                    if (enumerator.moveNext()) {
+                        if (enumerator.current() instanceof Array) {
+                            Utils.dispose(middleEnumerator);
+                            middleEnumerator = Enumerable.from(enumerator.current())
+                                .selectMany(Functions.Identity)
+                                .flatten()
+                                .getEnumerator();
+                            continue;
+                        }
+                        else {
+                            return this.yieldReturn(enumerator.current());
+                        }
+                    }
+
+                    return false;
+                }
+            },
+            function () {
+                try {
+                    Utils.dispose(enumerator);
+                }
+                finally {
+                    Utils.dispose(middleEnumerator);
+                }
+            });
+    });
+};
+
+Enumerable.prototype.pairwise = function (selector) {
+    var source = this;
+    selector = Utils.createLambda(selector);
+
+    return new Enumerable(function () {
+        var enumerator;
+
+        return new IEnumerator(
+            function () {
+                enumerator = source.getEnumerator();
+                enumerator.moveNext();
+            },
+            function () {
+                var prev = enumerator.current();
+                return (enumerator.moveNext())
+                    ? this.yieldReturn(selector(prev, enumerator.current()))
+                    : false;
+            },
+            function () { Utils.dispose(enumerator); });
+    });
+};
+
+// Overload:function(func)
+// Overload:function(seed,func<value,element>)
+Enumerable.prototype.scan = function (seed, func) {
+    var isUseSeed;
+    if (func == null) {
+        func = Utils.createLambda(seed);
+        isUseSeed = false;
+    } else {
+        func = Utils.createLambda(func);
+        isUseSeed = true;
+    }
+    var source = this;
+
+    return new Enumerable(function () {
+        var enumerator;
+        var value;
+        var isFirst = true;
+
+        return new IEnumerator(
+            function () { enumerator = source.getEnumerator(); },
+            function () {
+                if (isFirst) {
+                    isFirst = false;
+                    if (!isUseSeed) {
+                        if (enumerator.moveNext()) {
+                            return this.yieldReturn(value = enumerator.current());
+                        }
+                    }
+                    else {
+                        return this.yieldReturn(value = seed);
+                    }
+                }
+
+                return (enumerator.moveNext())
+                    ? this.yieldReturn(value = func(value, enumerator.current()))
+                    : false;
+            },
+            function () { Utils.dispose(enumerator); });
+    });
+};
+
+// Overload:function(selector<element>)
+// Overload:function(selector<element,index>)
+Enumerable.prototype.select = function (selector) {
+    selector = Utils.createLambda(selector);
+
+    if (selector.length <= 1) {
+        return new WhereSelectEnumerable(this, null, selector);
+    }
+    else {
+        var source = this;
+
+        return new Enumerable(function () {
+            var enumerator;
+            var index = 0;
+
+            return new IEnumerator(
+                function () { enumerator = source.getEnumerator(); },
+                function () {
+                    return (enumerator.moveNext())
+                        ? this.yieldReturn(selector(enumerator.current(), index++))
+                        : false;
+                },
+                function () { Utils.dispose(enumerator); });
+        });
+    }
+};
+
+// Overload:function(collectionSelector<element>)
+// Overload:function(collectionSelector<element,index>)
+// Overload:function(collectionSelector<element>,resultSelector)
+// Overload:function(collectionSelector<element,index>,resultSelector)
+Enumerable.prototype.selectMany = function (collectionSelector, resultSelector) {
+    var source = this;
+    collectionSelector = Utils.createLambda(collectionSelector);
+    if (resultSelector == null) resultSelector = function (a, b) { return b; };
+    resultSelector = Utils.createLambda(resultSelector);
+
+    return new Enumerable(function () {
+        var enumerator;
+        var middleEnumerator = undefined;
+        var index = 0;
+
+        return new IEnumerator(
+            function () { enumerator = source.getEnumerator(); },
+            function () {
+                if (middleEnumerator === undefined) {
+                    if (!enumerator.moveNext()) return false;
+                }
+                do {
+                    if (middleEnumerator == null) {
+                        var middleSeq = collectionSelector(enumerator.current(), index++);
+                        middleEnumerator = Enumerable.from(middleSeq).getEnumerator();
+                    }
+                    if (middleEnumerator.moveNext()) {
+                        return this.yieldReturn(resultSelector(enumerator.current(), middleEnumerator.current()));
+                    }
+                    Utils.dispose(middleEnumerator);
+                    middleEnumerator = null;
+                } while (enumerator.moveNext());
+                return false;
+            },
+            function () {
+                try {
+                    Utils.dispose(enumerator);
+                }
+                finally {
+                    Utils.dispose(middleEnumerator);
+                }
+            });
+    });
+};
+
+// Overload:function(predicate<element>)
+// Overload:function(predicate<element,index>)
+Enumerable.prototype.where = function (predicate) {
+    predicate = Utils.createLambda(predicate);
+
+    if (predicate.length <= 1) {
+        return new WhereEnumerable(this, predicate);
+    }
+    else {
+        var source = this;
+
+        return new Enumerable(function () {
+            var enumerator;
+            var index = 0;
+
+            return new IEnumerator(
+                function () { enumerator = source.getEnumerator(); },
+                function () {
+                    while (enumerator.moveNext()) {
+                        if (predicate(enumerator.current(), index++)) {
+                            return this.yieldReturn(enumerator.current());
+                        }
+                    }
+                    return false;
+                },
+                function () { Utils.dispose(enumerator); });
+        });
+    }
+};
+
+
+// Overload:function(selector<element>)
+// Overload:function(selector<element,index>)
+Enumerable.prototype.choose = function (selector) {
+    selector = Utils.createLambda(selector);
+    var source = this;
+
+    return new Enumerable(function () {
+        var enumerator;
+        var index = 0;
+
+        return new IEnumerator(
+            function () { enumerator = source.getEnumerator(); },
+            function () {
+                while (enumerator.moveNext()) {
+                    var result = selector(enumerator.current(), index++);
+                    if (result != null) {
+                        return this.yieldReturn(result);
+                    }
+                }
+                return this.yieldBreak();
+            },
+            function () { Utils.dispose(enumerator); });
+    });
+};
+
+Enumerable.prototype.ofType = function (type) {
+    var typeName;
+    switch (type) {
+        case Number:
+            typeName = Types.Number;
+            break;
+        case String:
+            typeName = Types.String;
+            break;
+        case Boolean:
+            typeName = Types.Boolean;
+            break;
+        case Function:
+            typeName = Types.Function;
+            break;
+        default:
+            typeName = null;
+            break;
+    }
+    return (typeName === null)
+        ? this.where(function (x) { return x instanceof type; })
+        : this.where(function (x) { return typeof x === typeName; });
+};
+
+// mutiple arguments, last one is selector, others are enumerable
+Enumerable.prototype.zip = function () {
+    var args = arguments;
+    var selector = Utils.createLambda(arguments[arguments.length - 1]);
+
+    var source = this;
+    // optimized case:argument is 2
+    if (arguments.length == 2) {
+        var second = arguments[0];
+
+        return new Enumerable(function () {
+            var firstEnumerator;
+            var secondEnumerator;
+            var index = 0;
+
+            return new IEnumerator(
+                function () {
+                    firstEnumerator = source.getEnumerator();
+                    secondEnumerator = Enumerable.from(second).getEnumerator();
+                },
+                function () {
+                    if (firstEnumerator.moveNext() && secondEnumerator.moveNext()) {
+                        return this.yieldReturn(selector(firstEnumerator.current(), secondEnumerator.current(), index++));
+                    }
+                    return false;
+                },
+                function () {
+                    try {
+                        Utils.dispose(firstEnumerator);
+                    } finally {
+                        Utils.dispose(secondEnumerator);
+                    }
+                });
+        });
+    }
+    else {
+        return new Enumerable(function () {
+            var enumerators;
+            var index = 0;
+
+            return new IEnumerator(
+                function () {
+                    var array = Enumerable.make(source)
+                        .concat(Enumerable.from(args).takeExceptLast().select(Enumerable.from))
+                        .select(function (x) { return x.getEnumerator() })
+                        .toArray();
+                    enumerators = Enumerable.from(array);
+                },
+                function () {
+                    if (enumerators.all(function (x) { return x.moveNext() })) {
+                        var array = enumerators
+                            .select(function (x) { return x.current() })
+                            .toArray();
+                        array.push(index++);
+                        return this.yieldReturn(selector.apply(null, array));
+                    }
+                    else {
+                        return this.yieldBreak();
+                    }
+                },
+                function () {
+                    Enumerable.from(enumerators).forEach(Utils.dispose);
+                });
+        });
+    }
+};
+
+// mutiple arguments
+Enumerable.prototype.merge = function () {
+    var args = arguments;
+    var source = this;
+
+    return new Enumerable(function () {
+        var enumerators;
+        var index = -1;
+
+        return new IEnumerator(
+            function () {
+                enumerators = Enumerable.make(source)
+                    .concat(Enumerable.from(args).select(Enumerable.from))
+                    .select(function (x) { return x.getEnumerator() })
+                    .toArray();
+            },
+            function () {
+                while (enumerators.length > 0) {
+                    index = (index >= enumerators.length - 1) ? 0 : index + 1;
+                    var enumerator = enumerators[index];
+
+                    if (enumerator.moveNext()) {
+                        return this.yieldReturn(enumerator.current());
+                    }
+                    else {
+                        enumerator.dispose();
+                        enumerators.splice(index--, 1);
+                    }
+                }
+                return this.yieldBreak();
+            },
+            function () {
+                Enumerable.from(enumerators).forEach(Utils.dispose);
+            });
+    });
+};
+
+////////////////
+// Join Methods
+
+// Overload:function (inner, outerKeySelector, innerKeySelector, resultSelector)
+// Overload:function (inner, outerKeySelector, innerKeySelector, resultSelector, compareSelector)
+Enumerable.prototype.join = function (inner, outerKeySelector, innerKeySelector, resultSelector, compareSelector) {
+    outerKeySelector = Utils.createLambda(outerKeySelector);
+    innerKeySelector = Utils.createLambda(innerKeySelector);
+    resultSelector = Utils.createLambda(resultSelector);
+    compareSelector = Utils.createLambda(compareSelector);
+    var source = this;
+
+    return new Enumerable(function () {
+        var outerEnumerator;
+        var lookup;
+        var innerElements = null;
+        var innerCount = 0;
+
+        return new IEnumerator(
+            function () {
+                outerEnumerator = source.getEnumerator();
+                lookup = Enumerable.from(inner).toLookup(innerKeySelector, Functions.Identity, compareSelector);
+            },
+            function () {
+                while (true) {
+                    if (innerElements != null) {
+                        var innerElement = innerElements[innerCount++];
+                        if (innerElement !== undefined) {
+                            return this.yieldReturn(resultSelector(outerEnumerator.current(), innerElement));
+                        }
+
+                        innerElement = null;
+                        innerCount = 0;
+                    }
+
+                    if (outerEnumerator.moveNext()) {
+                        var key = outerKeySelector(outerEnumerator.current());
+                        innerElements = lookup.get(key).toArray();
+                    } else {
+                        return false;
+                    }
+                }
+            },
+            function () { Utils.dispose(outerEnumerator); });
+    });
+};
+
+// Overload:function (inner, outerKeySelector, innerKeySelector, resultSelector)
+// Overload:function (inner, outerKeySelector, innerKeySelector, resultSelector, compareSelector)
+Enumerable.prototype.leftJoin = function (inner, outerKeySelector, innerKeySelector, resultSelector, compareSelector) {
+    outerKeySelector = Utils.createLambda(outerKeySelector);
+    innerKeySelector = Utils.createLambda(innerKeySelector);
+    resultSelector = Utils.createLambda(resultSelector);
+    compareSelector = Utils.createLambda(compareSelector);
+    var source = this;
+
+    return new Enumerable(function () {
+        var outerEnumerator;
+        var lookup;
+        var innerElements = null;
+        var innerCount = 0;
+
+        return new IEnumerator(
+            function () {
+                outerEnumerator = source.getEnumerator();
+                lookup = Enumerable.from(inner).toLookup(innerKeySelector, Functions.Identity, compareSelector);
+            },
+            function () {
+                while (true) {
+                    if (innerElements != null) {
+                        var innerElement = innerElements[innerCount++];
+                        if (innerElement !== undefined) {
+                            return this.yieldReturn(resultSelector(outerEnumerator.current(), innerElement));
+                        }
+
+                        innerElement = null;
+                        innerCount = 0;
+                    }
+
+                    if (outerEnumerator.moveNext()) {
+                        var key = outerKeySelector(outerEnumerator.current());
+                        innerElements = lookup.get(key).toArray();
+                        // execute once if innerElements is NULL
+                        if (innerElements == null || innerElements.length == 0) {
+                            return this.yieldReturn(resultSelector(outerEnumerator.current(), null));
+                        }
+                    } else {
+                        return false;
+                    }
+                }
+            },
+            function () { Utils.dispose(outerEnumerator); });
+    });
+};
+
+// Overload:function (inner, outerKeySelector, innerKeySelector, resultSelector)
+// Overload:function (inner, outerKeySelector, innerKeySelector, resultSelector, compareSelector)
+Enumerable.prototype.groupJoin = function (inner, outerKeySelector, innerKeySelector, resultSelector, compareSelector) {
+    outerKeySelector = Utils.createLambda(outerKeySelector);
+    innerKeySelector = Utils.createLambda(innerKeySelector);
+    resultSelector = Utils.createLambda(resultSelector);
+    compareSelector = Utils.createLambda(compareSelector);
+    var source = this;
+
+    return new Enumerable(function () {
+        var enumerator = source.getEnumerator();
+        var lookup = null;
+
+        return new IEnumerator(
+            function () {
+                enumerator = source.getEnumerator();
+                lookup = Enumerable.from(inner).toLookup(innerKeySelector, Functions.Identity, compareSelector);
+            },
+            function () {
+                if (enumerator.moveNext()) {
+                    var innerElement = lookup.get(outerKeySelector(enumerator.current()));
+                    return this.yieldReturn(resultSelector(enumerator.current(), innerElement));
+                }
+                return false;
+            },
+            function () { Utils.dispose(enumerator); });
+    });
+};
+
+///////////////
+// Set Methods
+
+Enumerable.prototype.all = function (predicate) {
+    predicate = Utils.createLambda(predicate);
+
+    var result = true;
+    this.forEach(function (x) {
+        if (!predicate(x)) {
+            result = false;
+            return false; // break
+        }
+    });
+    return result;
+};
+
+// Overload:function()
+// Overload:function(predicate)
+Enumerable.prototype.any = function (predicate) {
+    predicate = Utils.createLambda(predicate);
+
+    var enumerator = this.getEnumerator();
+    try {
+        if (arguments.length == 0) return enumerator.moveNext(); // case:function()
+
+        while (enumerator.moveNext()) // case:function(predicate)
+        {
+            if (predicate(enumerator.current())) return true;
+        }
+        return false;
+    }
+    finally {
+        Utils.dispose(enumerator);
+    }
+};
+
+Enumerable.prototype.isEmpty = function () {
+    return !this.any();
+};
+
+// multiple arguments
+Enumerable.prototype.concat = function () {
+    var source = this;
+
+    if (arguments.length == 1) {
+        var second = arguments[0];
+
+        return new Enumerable(function () {
+            var firstEnumerator;
+            var secondEnumerator;
+
+            return new IEnumerator(
+                function () { firstEnumerator = source.getEnumerator(); },
+                function () {
+                    if (secondEnumerator == null) {
+                        if (firstEnumerator.moveNext()) return this.yieldReturn(firstEnumerator.current());
+                        secondEnumerator = Enumerable.from(second).getEnumerator();
+                    }
+                    if (secondEnumerator.moveNext()) return this.yieldReturn(secondEnumerator.current());
+                    return false;
+                },
+                function () {
+                    try {
+                        Utils.dispose(firstEnumerator);
+                    }
+                    finally {
+                        Utils.dispose(secondEnumerator);
+                    }
+                });
+        });
+    }
+    else {
+        var args = arguments;
+
+        return new Enumerable(function () {
+            var enumerators;
+
+            return new IEnumerator(
+                function () {
+                    enumerators = Enumerable.make(source)
+                        .concat(Enumerable.from(args).select(Enumerable.from))
+                        .select(function (x) { return x.getEnumerator() })
+                        .toArray();
+                },
+                function () {
+                    while (enumerators.length > 0) {
+                        var enumerator = enumerators[0];
+
+                        if (enumerator.moveNext()) {
+                            return this.yieldReturn(enumerator.current());
+                        }
+                        else {
+                            enumerator.dispose();
+                            enumerators.splice(0, 1);
+                        }
+                    }
+                    return this.yieldBreak();
+                },
+                function () {
+                    Enumerable.from(enumerators).forEach(Utils.dispose);
+                });
+        });
+    }
+};
+
+Enumerable.prototype.insert = function (index, second) {
+    var source = this;
+
+    return new Enumerable(function () {
+        var firstEnumerator;
+        var secondEnumerator;
+        var count = 0;
+        var isEnumerated = false;
+
+        return new IEnumerator(
+            function () {
+                firstEnumerator = source.getEnumerator();
+                secondEnumerator = Enumerable.from(second).getEnumerator();
+            },
+            function () {
+                if (count == index && secondEnumerator.moveNext()) {
+                    isEnumerated = true;
+                    return this.yieldReturn(secondEnumerator.current());
+                }
+                if (firstEnumerator.moveNext()) {
+                    count++;
+                    return this.yieldReturn(firstEnumerator.current());
+                }
+                if (!isEnumerated && secondEnumerator.moveNext()) {
+                    return this.yieldReturn(secondEnumerator.current());
+                }
+                return false;
+            },
+            function () {
+                try {
+                    Utils.dispose(firstEnumerator);
+                }
+                finally {
+                    Utils.dispose(secondEnumerator);
+                }
+            });
+    });
+};
+
+Enumerable.prototype.alternate = function (alternateValueOrSequence) {
+    var source = this;
+
+    return new Enumerable(function () {
+        var buffer;
+        var enumerator;
+        var alternateSequence;
+        var alternateEnumerator;
+
+        return new IEnumerator(
+            function () {
+                if (alternateValueOrSequence instanceof Array || alternateValueOrSequence.getEnumerator != null) {
+                    alternateSequence = Enumerable.from(Enumerable.from(alternateValueOrSequence).toArray()); // freeze
+                }
+                else {
+                    alternateSequence = Enumerable.make(alternateValueOrSequence);
+                }
+                enumerator = source.getEnumerator();
+                if (enumerator.moveNext()) buffer = enumerator.current();
+            },
+            function () {
+                while (true) {
+                    if (alternateEnumerator != null) {
+                        if (alternateEnumerator.moveNext()) {
+                            return this.yieldReturn(alternateEnumerator.current());
+                        }
+                        else {
+                            alternateEnumerator = null;
+                        }
+                    }
+
+                    if (buffer == null && enumerator.moveNext()) {
+                        buffer = enumerator.current(); // hasNext
+                        alternateEnumerator = alternateSequence.getEnumerator();
+                        continue; // GOTO
+                    }
+                    else if (buffer != null) {
+                        var retVal = buffer;
+                        buffer = null;
+                        return this.yieldReturn(retVal);
+                    }
+
+                    return this.yieldBreak();
+                }
+            },
+            function () {
+                try {
+                    Utils.dispose(enumerator);
+                }
+                finally {
+                    Utils.dispose(alternateEnumerator);
+                }
+            });
+    });
+};
+
+// Overload:function(value)
+// Overload:function(value, compareSelector)
+Enumerable.prototype.contains = function (value, compareSelector) {
+    compareSelector = Utils.createLambda(compareSelector);
+    var enumerator = this.getEnumerator();
+    try {
+        while (enumerator.moveNext()) {
+            if (compareSelector(enumerator.current()) === value) return true;
+        }
+        return false;
+    }
+    finally {
+        Utils.dispose(enumerator);
+    }
+};
+
+Enumerable.prototype.defaultIfEmpty = function (defaultValue) {
+    var source = this;
+    if (defaultValue === undefined) defaultValue = null;
+
+    return new Enumerable(function () {
+        var enumerator;
+        var isFirst = true;
+
+        return new IEnumerator(
+            function () { enumerator = source.getEnumerator(); },
+            function () {
+                if (enumerator.moveNext()) {
+                    isFirst = false;
+                    return this.yieldReturn(enumerator.current());
+                }
+                else if (isFirst) {
+                    isFirst = false;
+                    return this.yieldReturn(defaultValue);
+                }
+                return false;
+            },
+            function () { Utils.dispose(enumerator); });
+    });
+};
+
+// Overload:function()
+// Overload:function(compareSelector)
+Enumerable.prototype.distinct = function (compareSelector) {
+    return this.except(Enumerable.empty(), compareSelector);
+};
+
+Enumerable.prototype.distinctUntilChanged = function (compareSelector) {
+    compareSelector = Utils.createLambda(compareSelector);
+    var source = this;
+
+    return new Enumerable(function () {
+        var enumerator;
+        var compareKey;
+        var initial;
+
+        return new IEnumerator(
+            function () {
+                enumerator = source.getEnumerator();
+            },
+            function () {
+                while (enumerator.moveNext()) {
+                    var key = compareSelector(enumerator.current());
+
+                    if (initial) {
+                        initial = false;
+                        compareKey = key;
+                        return this.yieldReturn(enumerator.current());
+                    }
+
+                    if (compareKey === key) {
+                        continue;
+                    }
+
+                    compareKey = key;
+                    return this.yieldReturn(enumerator.current());
+                }
+                return this.yieldBreak();
+            },
+            function () { Utils.dispose(enumerator); });
+    });
+};
+
+// Overload:function(second)
+// Overload:function(second, compareSelector)
+Enumerable.prototype.except = function (second, compareSelector) {
+    compareSelector = Utils.createLambda(compareSelector);
+    var source = this;
+
+    return new Enumerable(function () {
+        var enumerator;
+        var keys;
+
+        return new IEnumerator(
+            function () {
+                enumerator = source.getEnumerator();
+                keys = new Dictionary(compareSelector);
+                Enumerable.from(second).forEach(function (key) { keys.add(key); });
+            },
+            function () {
+                while (enumerator.moveNext()) {
+                    var current = enumerator.current();
+                    if (!keys.contains(current)) {
+                        keys.add(current);
+                        return this.yieldReturn(current);
+                    }
+                }
+                return false;
+            },
+            function () { Utils.dispose(enumerator); });
+    });
+};
+
+// Overload:function(second)
+// Overload:function(second, compareSelector)
+Enumerable.prototype.intersect = function (second, compareSelector) {
+    compareSelector = Utils.createLambda(compareSelector);
+    var source = this;
+
+    return new Enumerable(function () {
+        var enumerator;
+        var keys;
+        var outs;
+
+        return new IEnumerator(
+            function () {
+                enumerator = source.getEnumerator();
+
+                keys = new Dictionary(compareSelector);
+                Enumerable.from(second).forEach(function (key) { keys.add(key); });
+                outs = new Dictionary(compareSelector);
+            },
+            function () {
+                while (enumerator.moveNext()) {
+                    var current = enumerator.current();
+                    if (!outs.contains(current) && keys.contains(current)) {
+                        outs.add(current);
+                        return this.yieldReturn(current);
+                    }
+                }
+                return false;
+            },
+            function () { Utils.dispose(enumerator); });
+    });
+};
+
+// Overload:function(second)
+// Overload:function(second, compareSelector)
+Enumerable.prototype.sequenceEqual = function (second, compareSelector) {
+    compareSelector = Utils.createLambda(compareSelector);
+
+    var firstEnumerator = this.getEnumerator();
+    try {
+        var secondEnumerator = Enumerable.from(second).getEnumerator();
+        try {
+            while (firstEnumerator.moveNext()) {
+                if (!secondEnumerator.moveNext()
+                    || compareSelector(firstEnumerator.current()) !== compareSelector(secondEnumerator.current())) {
+                    return false;
+                }
+            }
+
+            if (secondEnumerator.moveNext()) return false;
+            return true;
+        }
+        finally {
+            Utils.dispose(secondEnumerator);
+        }
+    }
+    finally {
+        Utils.dispose(firstEnumerator);
+    }
+};
+
+Enumerable.prototype.union = function (second, compareSelector) {
+    compareSelector = Utils.createLambda(compareSelector);
+    var source = this;
+
+    return new Enumerable(function () {
+        var firstEnumerator;
+        var secondEnumerator;
+        var keys;
+
+        return new IEnumerator(
+            function () {
+                firstEnumerator = source.getEnumerator();
+                keys = new Dictionary(compareSelector);
+            },
+            function () {
+                var current;
+                if (secondEnumerator === undefined) {
+                    while (firstEnumerator.moveNext()) {
+                        current = firstEnumerator.current();
+                        if (!keys.contains(current)) {
+                            keys.add(current);
+                            return this.yieldReturn(current);
+                        }
+                    }
+                    secondEnumerator = Enumerable.from(second).getEnumerator();
+                }
+                while (secondEnumerator.moveNext()) {
+                    current = secondEnumerator.current();
+                    if (!keys.contains(current)) {
+                        keys.add(current);
+                        return this.yieldReturn(current);
+                    }
+                }
+                return false;
+            },
+            function () {
+                try {
+                    Utils.dispose(firstEnumerator);
+                }
+                finally {
+                    Utils.dispose(secondEnumerator);
+                }
+            });
+    });
+};
+
+////////////////////
+// Ordering Methods
+
+Enumerable.prototype.orderBy = function (keySelector, comparer) {
+    return new OrderedEnumerable(this, keySelector, comparer, false);
+};
+
+Enumerable.prototype.orderByDescending = function (keySelector, comparer) {
+    return new OrderedEnumerable(this, keySelector, comparer, true);
+};
+
+Enumerable.prototype.reverse = function () {
+    var source = this;
+
+    return new Enumerable(function () {
+        var buffer;
+        var index;
+
+        return new IEnumerator(
+            function () {
+                buffer = source.toArray();
+                index = buffer.length;
+            },
+            function () {
+                return (index > 0)
+                    ? this.yieldReturn(buffer[--index])
+                    : false;
+            },
+            Functions.Blank);
+    });
+};
+
+Enumerable.prototype.shuffle = function () {
+    var source = this;
+
+    return new Enumerable(function () {
+        var buffer;
+
+        return new IEnumerator(
+            function () { buffer = source.toArray(); },
+            function () {
+                if (buffer.length > 0) {
+                    var i = Math.floor(Math.random() * buffer.length);
+                    return this.yieldReturn(buffer.splice(i, 1)[0]);
+                }
+                return false;
+            },
+            Functions.Blank);
+    });
+};
+
+Enumerable.prototype.weightedSample = function (weightSelector) {
+    weightSelector = Utils.createLambda(weightSelector);
+    var source = this;
+
+    return new Enumerable(function () {
+        var sortedByBound;
+        var totalWeight = 0;
+
+        return new IEnumerator(
+            function () {
+                sortedByBound = source
+                    .choose(function (x) {
+                        var weight = weightSelector(x);
+                        if (weight <= 0) return null; // ignore 0
+
+                        totalWeight += weight;
+                        return { value: x, bound: totalWeight };
+                    })
+                    .toArray();
+            },
+            function () {
+                if (sortedByBound.length > 0) {
+                    var draw = Math.floor(Math.random() * totalWeight) + 1;
+
+                    var lower = -1;
+                    var upper = sortedByBound.length;
+                    while (upper - lower > 1) {
+                        var index = Math.floor((lower + upper) / 2);
+                        if (sortedByBound[index].bound >= draw) {
+                            upper = index;
+                        }
+                        else {
+                            lower = index;
+                        }
+                    }
+
+                    return this.yieldReturn(sortedByBound[upper].value);
+                }
+
+                return this.yieldBreak();
+            },
+            Functions.Blank);
+    });
+};
+
+////////////////////
+// Grouping Methods
+
+// Overload:function(keySelector)
+// Overload:function(keySelector,elementSelector)
+// Overload:function(keySelector,elementSelector,resultSelector)
+// Overload:function(keySelector,elementSelector,resultSelector,compareSelector)
+Enumerable.prototype.groupBy = function (keySelector, elementSelector, resultSelector, compareSelector) {
+    var source = this;
+    keySelector = Utils.createLambda(keySelector);
+    elementSelector = Utils.createLambda(elementSelector);
+    if (resultSelector != null) resultSelector = Utils.createLambda(resultSelector);
+    compareSelector = Utils.createLambda(compareSelector);
+
+    return new Enumerable(function () {
+        var enumerator;
+
+        return new IEnumerator(
+            function () {
+                enumerator = source.toLookup(keySelector, elementSelector, compareSelector)
+                    .toEnumerable()
+                    .getEnumerator();
+            },
+            function () {
+                while (enumerator.moveNext()) {
+                    return (resultSelector == null)
+                        ? this.yieldReturn(enumerator.current())
+                        : this.yieldReturn(resultSelector(enumerator.current().key(), enumerator.current()));
+                }
+                return false;
+            },
+            function () { Utils.dispose(enumerator); });
+    });
+};
+
+// Overload:function(keySelector)
+// Overload:function(keySelector,elementSelector)
+// Overload:function(keySelector,elementSelector,resultSelector)
+// Overload:function(keySelector,elementSelector,resultSelector,compareSelector)
+Enumerable.prototype.partitionBy = function (keySelector, elementSelector, resultSelector, compareSelector) {
+    var source = this;
+    keySelector = Utils.createLambda(keySelector);
+    elementSelector = Utils.createLambda(elementSelector);
+    compareSelector = Utils.createLambda(compareSelector);
+    var hasResultSelector;
+    if (resultSelector == null) {
+        hasResultSelector = false;
+        resultSelector = function (key, group) { return new Grouping(key, group); };
+    }
+    else {
+        hasResultSelector = true;
+        resultSelector = Utils.createLambda(resultSelector);
+    }
+
+    return new Enumerable(function () {
+        var enumerator;
+        var key;
+        var compareKey;
+        var group = [];
+
+        return new IEnumerator(
+            function () {
+                enumerator = source.getEnumerator();
+                if (enumerator.moveNext()) {
+                    key = keySelector(enumerator.current());
+                    compareKey = compareSelector(key);
+                    group.push(elementSelector(enumerator.current()));
+                }
+            },
+            function () {
+                var hasNext;
+                while ((hasNext = enumerator.moveNext()) == true) {
+                    if (compareKey === compareSelector(keySelector(enumerator.current()))) {
+                        group.push(elementSelector(enumerator.current()));
+                    }
+                    else break;
+                }
+
+                if (group.length > 0) {
+                    var result = (hasResultSelector)
+                        ? resultSelector(key, Enumerable.from(group))
+                        : resultSelector(key, group);
+                    if (hasNext) {
+                        key = keySelector(enumerator.current());
+                        compareKey = compareSelector(key);
+                        group = [elementSelector(enumerator.current())];
+                    }
+                    else group = [];
+
+                    return this.yieldReturn(result);
+                }
+
+                return false;
+            },
+            function () { Utils.dispose(enumerator); });
+    });
+};
+
+Enumerable.prototype.buffer = function (count) {
+    var source = this;
+
+    return new Enumerable(function () {
+        var enumerator;
+
+        return new IEnumerator(
+            function () { enumerator = source.getEnumerator(); },
+            function () {
+                var array = [];
+                var index = 0;
+                while (enumerator.moveNext()) {
+                    array.push(enumerator.current());
+                    if (++index >= count) return this.yieldReturn(array);
+                }
+                if (array.length > 0) return this.yieldReturn(array);
+                return false;
+            },
+            function () { Utils.dispose(enumerator); });
+    });
+};
+
+/////////////////////
+// Aggregate Methods
+
+// Overload:function(func)
+// Overload:function(seed,func)
+// Overload:function(seed,func,resultSelector)
+Enumerable.prototype.aggregate = function (seed, func, resultSelector) {
+    resultSelector = Utils.createLambda(resultSelector);
+    return resultSelector(this.scan(seed, func, resultSelector).last());
+};
+
+// Overload:function()
+// Overload:function(selector)
+Enumerable.prototype.average = function (selector) {
+    selector = Utils.createLambda(selector);
+
+    var sum = 0;
+    var count = 0;
+    this.forEach(function (x) {
+        sum += selector(x);
+        ++count;
+    });
+
+    return sum / count;
+};
+
+// Overload:function()
+// Overload:function(predicate)
+Enumerable.prototype.count = function (predicate) {
+    predicate = (predicate == null) ? Functions.True : Utils.createLambda(predicate);
+
+    var count = 0;
+    this.forEach(function (x, i) {
+        if (predicate(x, i)) ++count;
+    });
+    return count;
+};
+
+// Overload:function()
+// Overload:function(selector)
+Enumerable.prototype.max = function (selector) {
+    if (selector == null) selector = Functions.Identity;
+    return this.select(selector).aggregate(function (a, b) { return (a > b) ? a : b; });
+};
+
+// Overload:function()
+// Overload:function(selector)
+Enumerable.prototype.min = function (selector) {
+    if (selector == null) selector = Functions.Identity;
+    return this.select(selector).aggregate(function (a, b) { return (a < b) ? a : b; });
+};
+
+Enumerable.prototype.maxBy = function (keySelector) {
+    keySelector = Utils.createLambda(keySelector);
+    return this.aggregate(function (a, b) { return (keySelector(a) > keySelector(b)) ? a : b; });
+};
+
+Enumerable.prototype.minBy = function (keySelector) {
+    keySelector = Utils.createLambda(keySelector);
+    return this.aggregate(function (a, b) { return (keySelector(a) < keySelector(b)) ? a : b; });
+};
+
+// Overload:function()
+// Overload:function(selector)
+Enumerable.prototype.sum = function (selector) {
+    if (selector == null) selector = Functions.Identity;
+    return this.select(selector).aggregate(0, function (a, b) { return a + b; });
+};
+
+//////////////////
+// Paging Methods
+
+Enumerable.prototype.elementAt = function (index) {
+    var value;
+    var found = false;
+    this.forEach(function (x, i) {
+        if (i == index) {
+            value = x;
+            found = true;
+            return false;
+        }
+    });
+
+    if (!found) throw new Error("index is less than 0 or greater than or equal to the number of elements in source.");
+    return value;
+};
+
+Enumerable.prototype.elementAtOrDefault = function (index, defaultValue) {
+    if (defaultValue === undefined) defaultValue = null;
+    var value;
+    var found = false;
+    this.forEach(function (x, i) {
+        if (i == index) {
+            value = x;
+            found = true;
+            return false;
+        }
+    });
+
+    return (!found) ? defaultValue : value;
+};
+
+// Overload:function()
+// Overload:function(predicate)
+Enumerable.prototype.first = function (predicate) {
+    if (predicate != null) return this.where(predicate).first();
+
+    var value;
+    var found = false;
+    this.forEach(function (x) {
+        value = x;
+        found = true;
+        return false;
+    });
+
+    if (!found) throw new Error("first:No element satisfies the condition.");
+    return value;
+};
+
+Enumerable.prototype.firstOrDefault = function (predicate, defaultValue) {
+    if (predicate !== undefined) {
+        if (typeof predicate === Types.Function || typeof Utils.createLambda(predicate) === Types.Function) {
+            return this.where(predicate).firstOrDefault(undefined, defaultValue);
+        }
+        defaultValue = predicate;
+    }
+
+    var value;
+    var found = false;
+    this.forEach(function (x) {
+        value = x;
+        found = true;
+        return false;
+    });
+    return (!found) ? defaultValue : value;
+};
+
+// Overload:function()
+// Overload:function(predicate)
+Enumerable.prototype.last = function (predicate) {
+    if (predicate != null) return this.where(predicate).last();
+
+    var value;
+    var found = false;
+    this.forEach(function (x) {
+        found = true;
+        value = x;
+    });
+
+    if (!found) throw new Error("last:No element satisfies the condition.");
+    return value;
+};
+
+Enumerable.prototype.lastOrDefault = function (predicate, defaultValue) {
+    if (predicate !== undefined) {
+        if (typeof predicate === Types.Function || typeof Utils.createLambda(predicate) === Types.Function) {
+            return this.where(predicate).lastOrDefault(undefined, defaultValue);
+        }
+        defaultValue = predicate;
+    }
+
+    var value;
+    var found = false;
+    this.forEach(function (x) {
+        found = true;
+        value = x;
+    });
+    return (!found) ? defaultValue : value;
+};
+
+// Overload:function()
+// Overload:function(predicate)
+Enumerable.prototype.single = function (predicate) {
+    if (predicate != null) return this.where(predicate).single();
+
+    var value;
+    var found = false;
+    this.forEach(function (x) {
+        if (!found) {
+            found = true;
+            value = x;
+        } else throw new Error("single:sequence contains more than one element.");
+    });
+
+    if (!found) throw new Error("single:No element satisfies the condition.");
+    return value;
+};
+
+// Overload:function(defaultValue)
+// Overload:function(defaultValue,predicate)
+Enumerable.prototype.singleOrDefault = function (predicate, defaultValue) {
+    if (defaultValue === undefined) defaultValue = null;
+    if (predicate != null) return this.where(predicate).singleOrDefault(null, defaultValue);
+
+    var value;
+    var found = false;
+    this.forEach(function (x) {
+        if (!found) {
+            found = true;
+            value = x;
+        } else throw new Error("single:sequence contains more than one element.");
+    });
+
+    return (!found) ? defaultValue : value;
+};
+
+Enumerable.prototype.skip = function (count) {
+    var source = this;
+
+    return new Enumerable(function () {
+        var enumerator;
+        var index = 0;
+
+        return new IEnumerator(
+            function () {
+                enumerator = source.getEnumerator();
+                while (index++ < count && enumerator.moveNext()) { }
+            },
+            function () {
+                return (enumerator.moveNext())
+                    ? this.yieldReturn(enumerator.current())
+                    : false;
+            },
+            function () { Utils.dispose(enumerator); });
+    });
+};
+
+// Overload:function(predicate<element>)
+// Overload:function(predicate<element,index>)
+Enumerable.prototype.skipWhile = function (predicate) {
+    predicate = Utils.createLambda(predicate);
+    var source = this;
+
+    return new Enumerable(function () {
+        var enumerator;
+        var index = 0;
+        var isSkipEnd = false;
+
+        return new IEnumerator(
+            function () { enumerator = source.getEnumerator(); },
+            function () {
+                while (!isSkipEnd) {
+                    if (enumerator.moveNext()) {
+                        if (!predicate(enumerator.current(), index++)) {
+                            isSkipEnd = true;
+                            return this.yieldReturn(enumerator.current());
+                        }
+                        continue;
+                    } else return false;
+                }
+
+                return (enumerator.moveNext())
+                    ? this.yieldReturn(enumerator.current())
+                    : false;
+
+            },
+            function () { Utils.dispose(enumerator); });
+    });
+};
+
+Enumerable.prototype.take = function (count) {
+    var source = this;
+
+    return new Enumerable(function () {
+        var enumerator;
+        var index = 0;
+
+        return new IEnumerator(
+            function () { enumerator = source.getEnumerator(); },
+            function () {
+                return (index++ < count && enumerator.moveNext())
+                    ? this.yieldReturn(enumerator.current())
+                    : false;
+            },
+            function () { Utils.dispose(enumerator); }
+        );
+    });
+};
+
+// Overload:function(predicate<element>)
+// Overload:function(predicate<element,index>)
+Enumerable.prototype.takeWhile = function (predicate) {
+    predicate = Utils.createLambda(predicate);
+    var source = this;
+
+    return new Enumerable(function () {
+        var enumerator;
+        var index = 0;
+
+        return new IEnumerator(
+            function () { enumerator = source.getEnumerator(); },
+            function () {
+                return (enumerator.moveNext() && predicate(enumerator.current(), index++))
+                    ? this.yieldReturn(enumerator.current())
+                    : false;
+            },
+            function () { Utils.dispose(enumerator); });
+    });
+};
+
+// Overload:function()
+// Overload:function(count)
+Enumerable.prototype.takeExceptLast = function (count) {
+    if (count == null) count = 1;
+    var source = this;
+
+    return new Enumerable(function () {
+        if (count <= 0) return source.getEnumerator(); // do nothing
+
+        var enumerator;
+        var q = [];
+
+        return new IEnumerator(
+            function () { enumerator = source.getEnumerator(); },
+            function () {
+                while (enumerator.moveNext()) {
+                    if (q.length == count) {
+                        q.push(enumerator.current());
+                        return this.yieldReturn(q.shift());
+                    }
+                    q.push(enumerator.current());
+                }
+                return false;
+            },
+            function () { Utils.dispose(enumerator); });
+    });
+};
+
+Enumerable.prototype.takeFromLast = function (count) {
+    if (count <= 0 || count == null) return Enumerable.empty();
+    var source = this;
+
+    return new Enumerable(function () {
+        var sourceEnumerator;
+        var enumerator;
+        var q = [];
+
+        return new IEnumerator(
+            function () { sourceEnumerator = source.getEnumerator(); },
+            function () {
+                while (sourceEnumerator.moveNext()) {
+                    if (q.length == count) q.shift();
+                    q.push(sourceEnumerator.current());
+                }
+                if (enumerator == null) {
+                    enumerator = Enumerable.from(q).getEnumerator();
+                }
+                return (enumerator.moveNext())
+                    ? this.yieldReturn(enumerator.current())
+                    : false;
+            },
+            function () { Utils.dispose(enumerator); });
+    });
+};
+
+// Overload:function(item)
+// Overload:function(predicate)
+Enumerable.prototype.indexOf = function (item) {
+    var found = null;
+
+    // item as predicate
+    if (typeof (item) === Types.Function) {
+        this.forEach(function (x, i) {
+            if (item(x, i)) {
+                found = i;
+                return false;
+            }
+        });
+    }
+    else {
+        this.forEach(function (x, i) {
+            if (x === item) {
+                found = i;
+                return false;
+            }
+        });
+    }
+
+    return (found !== null) ? found : -1;
+};
+
+// Overload:function(item)
+// Overload:function(predicate)
+Enumerable.prototype.lastIndexOf = function (item) {
+    var result = -1;
+
+    // item as predicate
+    if (typeof (item) === Types.Function) {
+        this.forEach(function (x, i) {
+            if (item(x, i)) result = i;
+        });
+    }
+    else {
+        this.forEach(function (x, i) {
+            if (x === item) result = i;
+        });
+    }
+
+    return result;
+};
+
+///////////////////
+// Convert Methods
+
+Enumerable.prototype.cast = function () {
+    return this;
+};
+
+Enumerable.prototype.asEnumerable = function () {
+    return Enumerable.from(this);
+};
+
+Enumerable.prototype.toArray = function () {
+    var array = [];
+    this.forEach(function (x) { array.push(x); });
+    return array;
+};
+
+// Overload:function(keySelector)
+// Overload:function(keySelector, elementSelector)
+// Overload:function(keySelector, elementSelector, compareSelector)
+Enumerable.prototype.toLookup = function (keySelector, elementSelector, compareSelector) {
+    keySelector = Utils.createLambda(keySelector);
+    elementSelector = Utils.createLambda(elementSelector);
+    compareSelector = Utils.createLambda(compareSelector);
+
+    var dict = new Dictionary(compareSelector);
+    this.forEach(function (x) {
+        var key = keySelector(x);
+        var element = elementSelector(x);
+
+        var array = dict.get(key);
+        if (array !== undefined) array.push(element);
+        else dict.add(key, [element]);
+    });
+    return new Lookup(dict);
+};
+
+Enumerable.prototype.toObject = function (keySelector, elementSelector) {
+    keySelector = Utils.createLambda(keySelector);
+    elementSelector = Utils.createLambda(elementSelector);
+
+    var obj = {};
+    this.forEach(function (x) {
+        obj[keySelector(x)] = elementSelector(x);
+    });
+    return obj;
+};
+
+// Overload:function(keySelector, elementSelector)
+// Overload:function(keySelector, elementSelector, compareSelector)
+Enumerable.prototype.toDictionary = function (keySelector, elementSelector, compareSelector) {
+    keySelector = Utils.createLambda(keySelector);
+    elementSelector = Utils.createLambda(elementSelector);
+    compareSelector = Utils.createLambda(compareSelector);
+
+    var dict = new Dictionary(compareSelector);
+    this.forEach(function (x) {
+        dict.add(keySelector(x), elementSelector(x));
+    });
+    return dict;
+};
+
+// Overload:function()
+// Overload:function(replacer)
+// Overload:function(replacer, space)
+Enumerable.prototype.toJSONString = function (replacer, space) {
+    if (typeof JSON === Types.Undefined || JSON.stringify == null) {
+        throw new Error("toJSONString can't find JSON.stringify. This works native JSON support Browser or include json2.js");
+    }
+    return JSON.stringify(this.toArray(), replacer, space);
+};
+
+// Overload:function()
+// Overload:function(separator)
+// Overload:function(separator,selector)
+Enumerable.prototype.toJoinedString = function (separator, selector) {
+    if (separator == null) separator = "";
+    if (selector == null) selector = Functions.Identity;
+
+    return this.select(selector).toArray().join(separator);
+};
+
+//////////////////
+// Action Methods
+
+// Overload:function(action<element>)
+// Overload:function(action<element,index>)
+Enumerable.prototype.doAction = function (action) {
+    var source = this;
+    action = Utils.createLambda(action);
+
+    return new Enumerable(function () {
+        var enumerator;
+        var index = 0;
+
+        return new IEnumerator(
+            function () { enumerator = source.getEnumerator(); },
+            function () {
+                if (enumerator.moveNext()) {
+                    action(enumerator.current(), index++);
+                    return this.yieldReturn(enumerator.current());
+                }
+                return false;
+            },
+            function () { Utils.dispose(enumerator); });
+    });
+};
+
+// Overload:function(action<element>)
+// Overload:function(action<element,index>)
+// Overload:function(func<element,bool>)
+// Overload:function(func<element,index,bool>)
+Enumerable.prototype.forEach = function (action) {
+    action = Utils.createLambda(action);
+
+    var index = 0;
+    var enumerator = this.getEnumerator();
+    try {
+        while (enumerator.moveNext()) {
+            if (action(enumerator.current(), index++) === false) break;
+        }
+    } finally {
+        Utils.dispose(enumerator);
+    }
+};
+
+Enumerable.prototype.force = function () {
+    var enumerator = this.getEnumerator();
+
+    try {
+        while (enumerator.moveNext()) { }
+    }
+    finally {
+        Utils.dispose(enumerator);
+    }
+};
+
+//////////////////////
+// Functional Methods
+
+Enumerable.prototype.letBind = function (func) {
+    func = Utils.createLambda(func);
+    var source = this;
+
+    return new Enumerable(function () {
+        var enumerator;
+
+        return new IEnumerator(
+            function () {
+                enumerator = Enumerable.from(func(source)).getEnumerator();
+            },
+            function () {
+                return (enumerator.moveNext())
+                    ? this.yieldReturn(enumerator.current())
+                    : false;
+            },
+            function () { Utils.dispose(enumerator); });
+    });
+};
+
+Enumerable.prototype.share = function () {
+    var source = this;
+    var sharedEnumerator;
+    var disposed = false;
+
+    return new DisposableEnumerable(function () {
+        return new IEnumerator(
+            function () {
+                if (sharedEnumerator == null) {
+                    sharedEnumerator = source.getEnumerator();
+                }
+            },
+            function () {
+                if (disposed) throw new Error("enumerator is disposed");
+
+                return (sharedEnumerator.moveNext())
+                    ? this.yieldReturn(sharedEnumerator.current())
+                    : false;
+            },
+            Functions.Blank
+        );
+    }, function () {
+        disposed = true;
+        Utils.dispose(sharedEnumerator);
+    });
+};
+
+Enumerable.prototype.memoize = function () {
+    var source = this;
+    var cache;
+    var enumerator;
+    var disposed = false;
+
+    return new DisposableEnumerable(function () {
+        var index = -1;
+
+        return new IEnumerator(
+            function () {
+                if (enumerator == null) {
+                    enumerator = source.getEnumerator();
+                    cache = [];
+                }
+            },
+            function () {
+                if (disposed) throw new Error("enumerator is disposed");
+
+                index++;
+                if (cache.length <= index) {
+                    return (enumerator.moveNext())
+                        ? this.yieldReturn(cache[index] = enumerator.current())
+                        : false;
+                }
+
+                return this.yieldReturn(cache[index]);
+            },
+            Functions.Blank
+        );
+    }, function () {
+        disposed = true;
+        Utils.dispose(enumerator);
+        cache = null;
+    });
+};
+
+// Iterator support (ES6 for..of)
+if (Utils.hasNativeIteratorSupport()) {
+    Enumerable.prototype[Symbol.iterator] = function () {
+        return {
+            enumerator: this.getEnumerator(),
+            next: function () {
+                if (this.enumerator.moveNext()) {
+                    return {
+                        done: false,
+                        value: this.enumerator.current()
+                    };
+                } else {
+                    return { done: true };
+                }
+            }
+        };
+    };
+}
+
+//////////////////////////
+// Error Handling Methods
+
+Enumerable.prototype.catchError = function (handler) {
+    handler = Utils.createLambda(handler);
+    var source = this;
+
+    return new Enumerable(function () {
+        var enumerator;
+
+        return new IEnumerator(
+            function () { enumerator = source.getEnumerator(); },
+            function () {
+                try {
+                    return (enumerator.moveNext())
+                        ? this.yieldReturn(enumerator.current())
+                        : false;
+                } catch (e) {
+                    handler(e);
+                    return false;
+                }
+            },
+            function () { Utils.dispose(enumerator); });
+    });
+};
+
+Enumerable.prototype.finallyAction = function (finallyAction) {
+    finallyAction = Utils.createLambda(finallyAction);
+    var source = this;
+
+    return new Enumerable(function () {
+        var enumerator;
+
+        return new IEnumerator(
+            function () { enumerator = source.getEnumerator(); },
+            function () {
+                return (enumerator.moveNext())
+                    ? this.yieldReturn(enumerator.current())
+                    : false;
+            },
+            function () {
+                try {
+                    Utils.dispose(enumerator);
+                } finally {
+                    finallyAction();
+                }
+            });
+    });
+};
+
+/////////////////
+// Debug Methods
+
+// Overload:function()
+// Overload:function(selector)
+Enumerable.prototype.log = function (selector) {
+    selector = Utils.createLambda(selector);
+
+    return this.doAction(function (item) {
+        if (typeof console !== Types.Undefined) {
+            console.log(selector(item));
+        }
+    });
+};
+
+// Overload:function()
+// Overload:function(message)
+// Overload:function(message,selector)
+Enumerable.prototype.trace = function (message, selector) {
+    if (message == null) message = "Trace";
+    selector = Utils.createLambda(selector);
+
+    return this.doAction(function (item) {
+        if (typeof console !== Types.Undefined) {
+            console.log(message, selector(item));
+        }
+    });
+};
+
+///////////
+// Private
+
+var OrderedEnumerable = function (source, keySelector, comparer, descending, parent) {
+    this.source = source;
+    this.keySelector = Utils.createLambda(keySelector);
+    this.descending = descending;
+    this.parent = parent;
+
+    if (comparer)
+        this.comparer = Utils.createLambda(comparer);
+};
+OrderedEnumerable.prototype = new Enumerable();
+
+OrderedEnumerable.prototype.createOrderedEnumerable = function (keySelector, comparer, descending) {
+    return new OrderedEnumerable(this.source, keySelector, comparer, descending, this);
+};
+
+OrderedEnumerable.prototype.thenBy = function (keySelector, comparer) {
+    return this.createOrderedEnumerable(keySelector, comparer, false);
+};
+
+OrderedEnumerable.prototype.thenByDescending = function (keySelector, comparer) {
+    return this.createOrderedEnumerable(keySelector, comparer, true);
+};
+
+OrderedEnumerable.prototype.getEnumerator = function () {
+    var self = this;
+    var buffer;
+    var indexes;
+    var index = 0;
+
+    return new IEnumerator(
+        function () {
+            buffer = [];
+            indexes = [];
+            self.source.forEach(function (item, index) {
+                buffer.push(item);
+                indexes.push(index);
+            });
+            var sortContext = SortContext.create(self, null);
+            sortContext.GenerateKeys(buffer);
+
+            indexes.sort(function (a, b) { return sortContext.compare(a, b); });
+        },
+        function () {
+            return (index < indexes.length)
+                ? this.yieldReturn(buffer[indexes[index++]])
+                : false;
+        },
+        Functions.Blank
+    );
+};
+
+var SortContext = function (keySelector, comparer, descending, child) {
+    this.keySelector = keySelector;
+    this.descending = descending;
+    this.child = child;
+    this.comparer = comparer;
+    this.keys = null;
+};
+
+SortContext.create = function (orderedEnumerable, currentContext) {
+    var context = new SortContext(
+        orderedEnumerable.keySelector, orderedEnumerable.comparer, orderedEnumerable.descending, currentContext
+    );
+
+    if (orderedEnumerable.parent != null) return SortContext.create(orderedEnumerable.parent, context);
+    return context;
+};
+
+SortContext.prototype.GenerateKeys = function (source) {
+    var len = source.length;
+    var keySelector = this.keySelector;
+    var keys = new Array(len);
+    for (var i = 0; i < len; i++) keys[i] = keySelector(source[i]);
+    this.keys = keys;
+
+    if (this.child != null) this.child.GenerateKeys(source);
+};
+
+SortContext.prototype.compare = function (index1, index2) {
+    var comparison = this.comparer ?
+        this.comparer(this.keys[index1], this.keys[index2]) :
+        Utils.compare(this.keys[index1], this.keys[index2]);
+
+    if (comparison == 0) {
+        if (this.child != null) return this.child.compare(index1, index2);
+        return Utils.compare(index1, index2);
+    }
+
+    return (this.descending) ? -comparison : comparison;
+};
+
+var DisposableEnumerable = function (getEnumerator, dispose) {
+    this.dispose = dispose;
+    Enumerable.call(this, getEnumerator);
+};
+DisposableEnumerable.prototype = new Enumerable();
+
+var ArrayEnumerable = function (source) {
+    this.getSource = function () { return source; };
+};
+ArrayEnumerable.prototype = new Enumerable();
+
+ArrayEnumerable.prototype.any = function (predicate) {
+    return (predicate == null)
+        ? (this.getSource().length > 0)
+        : Enumerable.prototype.any.apply(this, arguments);
+};
+
+ArrayEnumerable.prototype.count = function (predicate) {
+    return (predicate == null)
+        ? this.getSource().length
+        : Enumerable.prototype.count.apply(this, arguments);
+};
+
+ArrayEnumerable.prototype.elementAt = function (index) {
+    var source = this.getSource();
+    return (0 <= index && index < source.length)
+        ? source[index]
+        : Enumerable.prototype.elementAt.apply(this, arguments);
+};
+
+ArrayEnumerable.prototype.elementAtOrDefault = function (index, defaultValue) {
+    if (defaultValue === undefined) defaultValue = null;
+    var source = this.getSource();
+    return (0 <= index && index < source.length)
+        ? source[index]
+        : defaultValue;
+};
+
+ArrayEnumerable.prototype.first = function (predicate) {
+    var source = this.getSource();
+    return (predicate == null && source.length > 0)
+        ? source[0]
+        : Enumerable.prototype.first.apply(this, arguments);
+};
+
+ArrayEnumerable.prototype.firstOrDefault = function (predicate, defaultValue) {
+    if (predicate !== undefined) {
+        return Enumerable.prototype.firstOrDefault.apply(this, arguments);
+    }
+    defaultValue = predicate;
+
+    var source = this.getSource();
+    return source.length > 0 ? source[0] : defaultValue;
+};
+
+ArrayEnumerable.prototype.last = function (predicate) {
+    var source = this.getSource();
+    return (predicate == null && source.length > 0)
+        ? source[source.length - 1]
+        : Enumerable.prototype.last.apply(this, arguments);
+};
+
+ArrayEnumerable.prototype.lastOrDefault = function (predicate, defaultValue) {
+    if (predicate !== undefined) {
+        return Enumerable.prototype.lastOrDefault.apply(this, arguments);
+    }
+    defaultValue = predicate;
+
+    var source = this.getSource();
+    return source.length > 0 ? source[source.length - 1] : defaultValue;
+};
+
+ArrayEnumerable.prototype.skip = function (count) {
+    var source = this.getSource();
+
+    return new Enumerable(function () {
+        var index;
+
+        return new IEnumerator(
+            function () { index = (count < 0) ? 0 : count; },
+            function () {
+                return (index < source.length)
+                    ? this.yieldReturn(source[index++])
+                    : false;
+            },
+            Functions.Blank);
+    });
+};
+
+ArrayEnumerable.prototype.takeExceptLast = function (count) {
+    if (count == null) count = 1;
+    return this.take(this.getSource().length - count);
+};
+
+ArrayEnumerable.prototype.takeFromLast = function (count) {
+    return this.skip(this.getSource().length - count);
+};
+
+ArrayEnumerable.prototype.reverse = function () {
+    var source = this.getSource();
+
+    return new Enumerable(function () {
+        var index;
+
+        return new IEnumerator(
+            function () {
+                index = source.length;
+            },
+            function () {
+                return (index > 0)
+                    ? this.yieldReturn(source[--index])
+                    : false;
+            },
+            Functions.Blank);
+    });
+};
+
+ArrayEnumerable.prototype.sequenceEqual = function (second, compareSelector) {
+    if ((second instanceof ArrayEnumerable || second instanceof Array)
+        && compareSelector == null
+        && Enumerable.from(second).count() != this.count()) {
+        return false;
+    }
+
+    return Enumerable.prototype.sequenceEqual.apply(this, arguments);
+};
+
+ArrayEnumerable.prototype.toJoinedString = function (separator, selector) {
+    var source = this.getSource();
+    if (selector != null || !(source instanceof Array)) {
+        return Enumerable.prototype.toJoinedString.apply(this, arguments);
+    }
+
+    if (separator == null) separator = "";
+    return source.join(separator);
+};
+
+ArrayEnumerable.prototype.getEnumerator = function () {
+    var source = this.getSource();
+    var index = -1;
+
+    // fast and simple enumerator
+    return {
+        current: function () { return source[index]; },
+        moveNext: function () {
+            return ++index < source.length;
+        },
+        dispose: Functions.Blank
+    };
+};
+
+// optimization for multiple where and multiple select and whereselect
+
+var WhereEnumerable = function (source, predicate) {
+    this.prevSource = source;
+    this.prevPredicate = predicate; // predicate.length always <= 1
+};
+WhereEnumerable.prototype = new Enumerable();
+
+WhereEnumerable.prototype.where = function (predicate) {
+    predicate = Utils.createLambda(predicate);
+
+    if (predicate.length <= 1) {
+        var prevPredicate = this.prevPredicate;
+        var composedPredicate = function (x) { return prevPredicate(x) && predicate(x); };
+        return new WhereEnumerable(this.prevSource, composedPredicate);
+    }
+    else {
+        // if predicate use index, can't compose
+        return Enumerable.prototype.where.call(this, predicate);
+    }
+};
+
+WhereEnumerable.prototype.select = function (selector) {
+    selector = Utils.createLambda(selector);
+
+    return (selector.length <= 1)
+        ? new WhereSelectEnumerable(this.prevSource, this.prevPredicate, selector)
+        : Enumerable.prototype.select.call(this, selector);
+};
+
+WhereEnumerable.prototype.getEnumerator = function () {
+    var predicate = this.prevPredicate;
+    var source = this.prevSource;
+    var enumerator;
+
+    return new IEnumerator(
+        function () { enumerator = source.getEnumerator(); },
+        function () {
+            while (enumerator.moveNext()) {
+                if (predicate(enumerator.current())) {
+                    return this.yieldReturn(enumerator.current());
+                }
+            }
+            return false;
+        },
+        function () { Utils.dispose(enumerator); });
+};
+
+var WhereSelectEnumerable = function (source, predicate, selector) {
+    this.prevSource = source;
+    this.prevPredicate = predicate; // predicate.length always <= 1 or null
+    this.prevSelector = selector; // selector.length always <= 1
+};
+WhereSelectEnumerable.prototype = new Enumerable();
+
+WhereSelectEnumerable.prototype.where = function (predicate) {
+    predicate = Utils.createLambda(predicate);
+
+    return (predicate.length <= 1)
+        ? new WhereEnumerable(this, predicate)
+        : Enumerable.prototype.where.call(this, predicate);
+};
+
+WhereSelectEnumerable.prototype.select = function (selector) {
+    selector = Utils.createLambda(selector);
+
+    if (selector.length <= 1) {
+        var prevSelector = this.prevSelector;
+        var composedSelector = function (x) { return selector(prevSelector(x)); };
+        return new WhereSelectEnumerable(this.prevSource, this.prevPredicate, composedSelector);
+    }
+    else {
+        // if selector uses index, can't compose
+        return Enumerable.prototype.select.call(this, selector);
+    }
+};
+
+WhereSelectEnumerable.prototype.getEnumerator = function () {
+    var predicate = this.prevPredicate;
+    var selector = this.prevSelector;
+    var source = this.prevSource;
+    var enumerator;
+
+    return new IEnumerator(
+        function () { enumerator = source.getEnumerator(); },
+        function () {
+            while (enumerator.moveNext()) {
+                if (predicate == null || predicate(enumerator.current())) {
+                    return this.yieldReturn(selector(enumerator.current()));
+                }
+            }
+            return false;
+        },
+        function () { Utils.dispose(enumerator); });
+};
+
+///////////////
+// Collections
+
+var Dictionary = (function () {
+    // static utility methods
+    var callHasOwnProperty = function (target, key) {
+        return Object.prototype.hasOwnProperty.call(target, key);
+    };
+
+    var computeHashCode = function (obj) {
+        if (obj === null) return "null";
+        if (obj === undefined) return "undefined";
+
+        return (typeof obj.toString === Types.Function)
+            ? obj.toString()
+            : Object.prototype.toString.call(obj);
+    };
+
+    // LinkedList for Dictionary
+    var HashEntry = function (key, value) {
+        this.key = key;
+        this.value = value;
+        this.prev = null;
+        this.next = null;
+    };
+
+    var EntryList = function () {
+        this.first = null;
+        this.last = null;
+    };
+    EntryList.prototype =
+    {
+        addLast: function (entry) {
+            if (this.last != null) {
+                this.last.next = entry;
+                entry.prev = this.last;
+                this.last = entry;
+            } else this.first = this.last = entry;
+        },
+
+        replace: function (entry, newEntry) {
+            if (entry.prev != null) {
+                entry.prev.next = newEntry;
+                newEntry.prev = entry.prev;
+            } else this.first = newEntry;
+
+            if (entry.next != null) {
+                entry.next.prev = newEntry;
+                newEntry.next = entry.next;
+            } else this.last = newEntry;
+
+        },
+
+        remove: function (entry) {
+            if (entry.prev != null) entry.prev.next = entry.next;
+            else this.first = entry.next;
+
+            if (entry.next != null) entry.next.prev = entry.prev;
+            else this.last = entry.prev;
+        }
+    };
+
+    // Overload:function()
+    // Overload:function(compareSelector)
+    var Dictionary = function (compareSelector) {
+        this.countField = 0;
+        this.entryList = new EntryList();
+        this.buckets = {}; // as Dictionary<string,List<object>>
+        this.compareSelector = (compareSelector == null) ? Functions.Identity : compareSelector;
+    };
+    Dictionary.prototype =
+    {
+        add: function (key, value) {
+            var compareKey = this.compareSelector(key);
+            var hash = computeHashCode(compareKey);
+            var entry = new HashEntry(key, value);
+            if (callHasOwnProperty(this.buckets, hash)) {
+                var array = this.buckets[hash];
+                for (var i = 0; i < array.length; i++) {
+                    if (this.compareSelector(array[i].key) === compareKey) {
+                        this.entryList.replace(array[i], entry);
+                        array[i] = entry;
+                        return;
+                    }
+                }
+                array.push(entry);
+            } else {
+                this.buckets[hash] = [entry];
+            }
+            this.countField++;
+            this.entryList.addLast(entry);
+        },
+
+        get: function (key) {
+            var compareKey = this.compareSelector(key);
+            var hash = computeHashCode(compareKey);
+            if (!callHasOwnProperty(this.buckets, hash)) return undefined;
+
+            var array = this.buckets[hash];
+            for (var i = 0; i < array.length; i++) {
+                var entry = array[i];
+                if (this.compareSelector(entry.key) === compareKey) return entry.value;
+            }
+            return undefined;
+        },
+
+        set: function (key, value) {
+            var compareKey = this.compareSelector(key);
+            var hash = computeHashCode(compareKey);
+            if (callHasOwnProperty(this.buckets, hash)) {
+                var array = this.buckets[hash];
+                for (var i = 0; i < array.length; i++) {
+                    if (this.compareSelector(array[i].key) === compareKey) {
+                        var newEntry = new HashEntry(key, value);
+                        this.entryList.replace(array[i], newEntry);
+                        array[i] = newEntry;
+                        return true;
+                    }
+                }
+            }
+            return false;
+        },
+
+        contains: function (key) {
+            var compareKey = this.compareSelector(key);
+            var hash = computeHashCode(compareKey);
+            if (!callHasOwnProperty(this.buckets, hash)) return false;
+
+            var array = this.buckets[hash];
+            for (var i = 0; i < array.length; i++) {
+                if (this.compareSelector(array[i].key) === compareKey) return true;
+            }
+            return false;
+        },
+
+        clear: function () {
+            this.countField = 0;
+            this.buckets = {};
+            this.entryList = new EntryList();
+        },
+
+        remove: function (key) {
+            var compareKey = this.compareSelector(key);
+            var hash = computeHashCode(compareKey);
+            if (!callHasOwnProperty(this.buckets, hash)) return;
+
+            var array = this.buckets[hash];
+            for (var i = 0; i < array.length; i++) {
+                if (this.compareSelector(array[i].key) === compareKey) {
+                    this.entryList.remove(array[i]);
+                    array.splice(i, 1);
+                    if (array.length == 0) delete this.buckets[hash];
+                    this.countField--;
+                    return;
+                }
+            }
+        },
+
+        count: function () {
+            return this.countField;
+        },
+
+        toEnumerable: function () {
+            var self = this;
+            return new Enumerable(function () {
+                var currentEntry;
+
+                return new IEnumerator(
+                    function () { currentEntry = self.entryList.first; },
+                    function () {
+                        if (currentEntry != null) {
+                            var result = { key: currentEntry.key, value: currentEntry.value };
+                            currentEntry = currentEntry.next;
+                            return this.yieldReturn(result);
+                        }
+                        return false;
+                    },
+                    Functions.Blank);
+            });
+        }
+    };
+
+    return Dictionary;
+})();
+
+// dictionary = Dictionary<TKey, TValue[]>
+var Lookup = function (dictionary) {
+    this.count = function () {
+        return dictionary.count();
+    };
+    this.get = function (key) {
+        return Enumerable.from(dictionary.get(key));
+    };
+    this.contains = function (key) {
+        return dictionary.contains(key);
+    };
+    this.toEnumerable = function () {
+        return dictionary.toEnumerable().select(function (kvp) {
+            return new Grouping(kvp.key, kvp.value);
+        });
+    };
+};
+
+var Grouping = function (groupKey, elements) {
+    this.key = function () {
+        return groupKey;
+    };
+    ArrayEnumerable.call(this, elements);
+};
+Grouping.prototype = new ArrayEnumerable();
+
+exports._default = Enumerable;
diff --git a/data/test-misc.json b/data/test-misc.json
index 9f400ec..a018f23 100644
--- a/data/test-misc.json
+++ b/data/test-misc.json
@@ -36,7 +36,7 @@
     "tests": [
         {
             "id": "gtkserver_test",
-            "description": "GTK Server를 이용한 GUI(그래픽 사용자 인터페이스) 구현 가능 여부 확인",
+            "description": "Graphical User Interface (GUI) test with GTK server",
             "tags": ["GTK", "GTK"]
         },
         {
@@ -71,8 +71,13 @@
         },
         {
             "id": "string_split",
-            "description": "String.split test",
+            "description": "String.split() test",
             "tags": ["Assertion"]
+        },
+        {
+            "id": "linqjs",
+            "description": "linq.js (LINQ for JavaScript) test",
+            "tags": ["Library"]
         }
     ]
 }
diff --git a/testloader.js b/testloader.js
index 7e29a58..6a99367 100644
--- a/testloader.js
+++ b/testloader.js
@@ -934,6 +934,23 @@ var test_implements = {
             console.log(c);
             console.log(d);
         }
+    },
+    
+    "linqjs": function() {
+        var a = Enumerable.range(1, 10)
+            .where(function(i) { return i % 3 == 0; })
+            .select(function(i) { return i * 10; })
+        ;
+        console.log(a.toArray().join(','));
+        
+        var array = "monkey:red:apple:delicious:banana:long:train:fast:airplane:high:everest:sharp:seringue:painful".split(':');
+        var b = Enumerable.from(array).select(function(val, i) { 
+            return {
+                value: val,
+                index: i
+            }
+        });
+        console.log(JSON.stringify(b.toArray()));
     }
 };