X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=code%2Flambda_evaluator.mdwn;h=223195194d2f9478493e9cc03397253e272ed7af;hp=d39086fd257131bb012c1fa5f71191c387c23927;hb=7936567be1fea69bb7e1bb299bd3d1616b6e2dcc;hpb=f80471bc9bb0900caa27e86d06b4b93f17dd6469 diff --git a/code/lambda_evaluator.mdwn b/code/lambda_evaluator.mdwn index d39086fd..22319519 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)`. @@ -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).