Lambda Evaluator ---------------- There is now a [lambda evaluator](http://lambda.jimpryor.net/lambda-let.html) available. It 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*: `true` and `false` are pre-defined to their standard values. So too are the combinators `S`, `K`, `I`, `C`, `B`, `W`, and `T`. Finally, integers will automatically be converted to Church numerals. (`0` is `\s z. z`, `1` is `\s z. s z`, and so on.)

Under the hood
---------------

The interpreter is written in JavaScript (which is not closely related to Java), 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