X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=code%2Flambda_evaluator.mdwn;h=220f6139ccea052f84ff33f04b49773acef2ccf6;hp=d39086fd257131bb012c1fa5f71191c387c23927;hb=8cd2e41084d42df6db49d6ea9e3183c709a54837;hpb=f80471bc9bb0900caa27e86d06b4b93f17dd6469

diff --git a/code/lambda_evaluator.mdwn b/code/lambda_evaluator.mdwn
index d39086fd..220f6139 100644
--- a/code/lambda_evaluator.mdwn
+++ b/code/lambda_evaluator.mdwn
@@ -1,7 +1,7 @@
 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.)  
+(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)`.  
+*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)`.
 
@@ -19,7 +19,7 @@ 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.)
+*Constants*: The combinators `S`, `K`, `I`, `C`, `B`, `W`, `T`, `V`, `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.
 
@@ -109,12 +109,12 @@ 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 
+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: 
+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).
@@ -134,7 +134,7 @@ 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).
+*	The UPenn [Lambda Calculator](http://dylanbumford.com/LambdaCalculator/): Pedagogical software developed by Lucas Champollion and others. Linguistically oriented, uses types. Requires Java (many users will probably already have Java 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.
 *	[Matt Might's Lambda Evaluator](http://matt.might.net/articles/implementing-a-programming-language/) in Scheme (R5RS and Racket).