lambda.js: try trampolining evals

[lambda.git] / code / lambda.js

diff --git a/code/lambda.js b/code/lambda.js
index 609cce0..15a3cf8 100644 (file)
--- a/code/lambda.js
+++ b/code/lambda.js
@@ -207,11 +207,14 @@ function Lambda_var(variable) {
                        var res = left, x;
                        while (stack.length) {
                                x = stack.shift();
-                               res = new Lambda_app(res, x.eval_loop([], eta));
+                               // res = new Lambda_app(res, x.eval_loop([], eta));
+                               res = new Lambda_app(res, reduce(x, eta, false));
                        }
                        return res;
         }
-        return unwind(this, stack);
+        // return unwind(this, stack);
+               // post-processor, trampoline to, args
+               return [null, null, unwind(this, stack)];
     };
     this.eval_cbv = function (aggressive) {
         return this;
@@ -261,7 +264,9 @@ function Lambda_app(left, right) {
     this.eval_loop = function (stack, eta) {
         var new_stack = stack.slice(0);
         new_stack.unshift(this.right);
-        return this.left.eval_loop(new_stack, eta);
+        // return this.left.eval_loop(new_stack, eta);
+               // post-processor, trampoline to, args
+               return [null, this.left, new_stack, eta];
     };
     this.eval_cbv = function (aggressive) {
         var left = this.left.eval_cbv(aggressive);
@@ -354,17 +359,29 @@ function Lambda_lam(variable, body) {
         }
     };
     this.eval_loop = function (stack, eta) {
+               function post(evaluated_body) {
+                       var term = new Lambda_lam(this.bound, evaluated_body);
+                       if (eta) {
+                               return term.check_eta();
+                       } else {
+                               return term;
+                       }
+               }
         if (stack.length === 0) {
-            var term = new Lambda_lam(this.bound, this.body.eval_loop([], eta));
-            if (eta) {
-                return term.check_eta();
-            } else {
-                return term;
-            }
+//             var term = new Lambda_lam(this.bound, this.body.eval_loop([], eta));
+//             if (eta) {
+//                 return term.check_eta();
+//             } else {
+//                 return term;
+//             }
+                       // post-processor, trampoline to, args
+                       return [post, this.body, [], eta];      
         } else {
             var x = stack[0];
             var xs = stack.slice(1);
-            return subst(this.bound, x, this.body).eval_loop(xs, eta);
+            // return subst(this.bound, x, this.body).eval_loop(xs, eta);
+                       // post-processor, trampoline to, args
+                       return [null, subst(this.bound, x, this.body), xs, eta];
         }
     };
     this.eval_cbv = function (aggressive) {
@@ -414,7 +431,17 @@ function reduce(expr, eta, cbv) {
     if (cbv) {
         return expr.eval_cbv(cbv > 1);
     } else {
-        return expr.eval_loop([], eta);
+        // return expr.eval_loop([], eta);
+               var post = null, to_eval = expr, res = [[], eta];
+               while (to_eval !== null) {
+                       res = to_eval.eval_loop.apply(to_eval, res);
+                       post = res.shift();
+                       to_eval = res.shift();
+                       if (post) {
+                               res = post(res);
+                       }
+               }
+               return res[0];
     }
 }