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-This lambda evaluator will allow you to write lambda terms and evaluate (that is, normalize) them, and inspect the results.
-(This won't work in Racket, because Racket doesn't even try to represent the internal structure of a function in a human-readable way.)  
-
-*Lambda terms*: lambda terms are written with a backslash, thus: `((\x (\y x)) z)`.  
-
-If you click "Normalize", the system will try to produce a normal-form lambda expression that your original term reduces to (~~>). So `((\x (\y x)) z)` reduces to `(\y z)`.
-
-*Let*: in order to make building a more elaborate set of terms easier, it is possible to define values using `let`.
-In this toy system, `let`s should only be used at the beginning of a file.  If we have, for intance,
-
-    let true = (\x (\y x)) in
-    let false = (\x (\y y)) in
-    ((true yes) no)
-
-the result is `yes`.
-
-*Comments*: anything following a semicolon to the end of the line is ignored.
-Blank lines are fine.
-
-*Abbreviations*: In an earlier version, you couldn't use abbreviations. `\x y. y x x` had to be written `(\x (\y ((y x) x)))`. We've upgraded the parser though, so now it should be able to understand any lambda term that you can.
-
-*Constants*: The combinators `S`, `K`, `I`, `C`, `B`, `W`, `T`, `M` (aka <code>&omega;</code>) and `L` are pre-defined to their standard values. Also, integers will automatically be converted to Church numerals. (`0` is `\s z. z`, `1` is `\s z. s z`, and so on.)
-
-*Variables*: Variables must start with a letter and can continue with any sequence of letters, numbers, `_`, `-`, or `/`. They may optionally end with `?` or `!`. When the evaluator does alpha-conversion, it may change `x` into `x'` or `x''` and so on. But you should not attempt to use primed variable names yourself.
-
-
-<textarea id="INPUT" style="border: 2px solid black; color: black; font-family: monospace; height: 3in; overflow: auto; padding: 0.5em; width: 100%;">
-let true = \x y. x in
-let false = \x y. y in
-let and = \l r. l r false in
-(
-	(and true true yes no)
-	(and true false yes no)
-	(and false true yes no)
-	(and false false yes no)
-)
-</textarea>
-<input id="PARSE" value="Normalize" type="button">
-<input id="ETA" type="checkbox">do eta-reductions too
-<noscript><p>You may not see it because you have JavaScript turned off. Uffff!</p></noscript>
-<script src="/code/lambda.js"></script>
-<script src="/code/tokens.js"></script>
-<script src="/code/parse.js"></script>
-<script src="/code/json2.js"></script>
-<pre id="OUTPUT">
-</pre>
-<script>
-/*jslint evil: true */
-
-/*members create, error, message, name, prototype, stringify, toSource,
-    toString, write
-*/
-
-/*global JSON, make_parse, parse, source, tree */
-
-// Make a new object that inherits members from an existing object.
-
-if (typeof Object.create !== 'function') {
-    Object.create = function (o) {
-        function F() {}
-        F.prototype = o;
-        return new F();
-    };
-}
-
-// Transform a token object into an exception object and throw it.
-
-Object.prototype.error = function (message, t) {
-    t = t || this;
-    t.name = "SyntaxError";
-    t.message = message;
-    throw t;
-};
-
-
-(function () {
-    var parse = make_parse();
-
-    function go(source) {
-        var string, tree, expr, eta;
-        try {
-            tree = parse(source);
- //           string = JSON.stringify(tree, ['key', 'name', 'message', 'value', 'arity', 'first', 'second', 'third', 'fourth'], 4);
-			expr = tree.handler();
-            // string = JSON.stringify(expr, ['key', 'name', 'message', 'value', 'arity', 'first', 'second', 'tag', 'variable', 'left', 'right', 'bound', 'body' ], 4);
-//			string = expr.to_string() + "\n\n~~>\n\n";
-			string = '';
-			eta = document.getElementById('ETA').checked;
-			string = string + reduce(expr, eta, false).to_string();
-        } catch (e) {
-            string = JSON.stringify(e, ['name', 'message', 'from', 'to', 'key',
-                    'value', 'arity', 'first', 'second', 'third', 'fourth'], 4);
-        }
-        document.getElementById('OUTPUT').innerHTML = string
-            .replace(/&/g, '&amp;')
-            .replace(/[<]/g, '&lt;');
-    }
-
-    document.getElementById('PARSE').onclick = function (e) {
-        go(document.getElementById('INPUT').value);
-    };
-}());
-
-</script>
-
-
-
-Under the hood
----------------
-
-The interpreter is written in JavaScript and runs inside your browser.
-So if you decide to reduce a term that does not terminate (such as `((\x (x x)) (\x (x x)))`), it will be your 
-browser that stops responding, not the wiki server.
-
-The main code is [here](http://lambda.jimpryor.net/code/lambda.js). Suggestions for improvements welcome.
-
-The code is based on: 
-
-*	Chris Barker's JavaScript lambda calculator
-*	[Oleg Kiselyov's Haskell lambda calculator](http://okmij.org/ftp/Computation/lambda-calc.html#lambda-calculator-haskell).
-*	The top-down JavaScript lexer and parser at <http://javascript.crockford.com/tdop/index.html>.
-
-Improvements we hope to add:
-
-*	detecting some common cases of non-normalizing terms (the problem of determining in general whether a term will normalize is undecidable)
-*	returning results in combinator form (the evaluator already accepts combinators as input)
-*	displaying reductions one step at a time
-*	specifying the reduction order and depth
-*	allow other binders such as &forall; and &exist; (though these won't be interpreted as doing anything other than binding variables)
-
-Other Lambda Evaluators/Calculutors
------------------------------------
-
-*	[Peter Sestoft's Lambda calculus reducer](http://www.itu.dk/people/sestoft/lamreduce/index.html) Very nice! Allows you to select different evaluation strategies, and shows stepwise reductions.
-*	[Chris Barker's Lambda Tutorial](http://homepages.nyu.edu/~cb125/Lambda)
-*	[Penn Lambda Calculator](http://www.ling.upenn.edu/lambda/) Pedagogical software developed by Lucas Champollion, Josh Tauberer and Maribel Romero.  Linguistically oriented. Requires installing Java (Mac users will probably already have it installed).
-*	[Mike Thyer's Lambda Animator](http://thyer.name/lambda-animator/) Graphical tool for experimenting with different reduction strategies. Also requires installing Java, and Graphviz.
-