tweak lambda evaluator

Signed-off-by: Jim Pryor <profjim@jimpryor.net>

diff --git a/lambda_evaluator.mdwn b/lambda_evaluator.mdwn
index 3fba8fa..c0697ab 100644 (file)
--- a/lambda_evaluator.mdwn
+++ b/lambda_evaluator.mdwn
@@ -79,7 +79,7 @@ Object.prototype.error = function (message, t) {
     var parse = make_parse();
 
     function go(source) {
-        var string, tree, expr;
+        var string, tree, expr, eta;
         try {
             tree = parse(source);
  //           string = JSON.stringify(tree, ['key', 'name', 'message', 'value', 'arity', 'first', 'second', 'third', 'fourth'], 4);
@@ -87,7 +87,8 @@ Object.prototype.error = function (message, t) {
             // 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 = '';
-                       string = string + reduce(expr, document.getElementById('ETA').value, false).to_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);