X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?a=blobdiff_plain;f=lambda_evaluator.mdwn;h=c0697abd148f771170b18087c9af813f601cb8df;hb=efc414adb5e2372295701927bc1115afedf44ce7;hp=6d0866c7ccc9ada00559fc9164914d43ab832076;hpb=516417f5f9ac78553dd1788e263878ff6016f21d;p=lambda.git

diff --git a/lambda_evaluator.mdwn b/lambda_evaluator.mdwn
index 6d0866c7..c0697abd 100644
--- a/lambda_evaluator.mdwn
+++ b/lambda_evaluator.mdwn
@@ -22,7 +22,7 @@ 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*:  (NOT YET IMPLEMENTED!) The combinators `S`, `K`, `I`, `C`, `B`, `W`, and `T` 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`, and `T` 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.)
 
 
 
@@ -38,11 +38,12 @@ let and = \l r. l r false in
 )
 </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>
+<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>
@@ -78,12 +79,16 @@ Object.prototype.error = function (message, t) {
     var parse = make_parse();
 
     function go(source) {
-        var string, tree;
+        var string, tree, expr, eta;
         try {
             tree = parse(source);
-//             string = JSON.stringify(tree, ['key', 'name', 'message', 'value', 'arity', 'first', 'second', 'third', 'fourth'], 4);
-//             string = JSON.stringify(tree.handler(), ['key', 'name', 'message', 'value', 'arity', 'first', 'second', 'tag', 'variable', 'left', 'right', 'bound', 'body' ], 4);
-			string = tree.handler().to_string();
+ //           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').value === "on";
+			string = "("+eta+")"+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);
@@ -119,5 +124,4 @@ The code is based on:
 
 Improvements we hope to add soon: the ability to reduce Combinatory Logic combinators and report the result as combinators, rather than in lambda forms.
 
-For these assignments, you'll probably want to use a "lambda calculator" to check your work. This accepts any grammatical lambda expression and reduces it to normal form, when possible. See our [lambda-let page](/lambda-let.html),