tweak lambda evaluator

[lambda.git] / code / parse.js

diff --git a/code/parse.js b/code/parse.js
index cb412f7..8a4761b 100644 (file)
--- a/code/parse.js
+++ b/code/parse.js
@@ -34,14 +34,14 @@ var make_parse = function () {
         a = t.type;
         if (a === "name") {
             o = symbol_table[v];
-            if (o && typeof o !== 'function') {
-                a = "keyword";
-            } else {
+            if (!o || typeof o === 'function') {
                 o = symbol_table["(name)"];
+            } else {
+                a = o.arity || "keyword";
             }
         } else if (a ===  "number") {
-            o = symbol_table["(literal)"];
-            a = "literal";
+            o = symbol_table["(number)"];
+                       a = "literal";
         } else if (a === "operator") {
             o = symbol_table[v];
             if (!o) {
@@ -79,7 +79,6 @@ var make_parse = function () {
             s = Object.create(original_symbol);
             s.id = s.value = id;
             symbol_table[id] = s;
-                       print(s, s.arity);
         }
         return s;
     };
@@ -127,14 +126,13 @@ var make_parse = function () {
         return body;
     };
 
+    var number_handler = function () {
 
-    var itself = function () {
-        return this;
     };
 
     symbol("(end)");
     symbol("(name)").handler = name_handler;
-    symbol("(literal)").handler = itself;
+    symbol("(number)").handler = number_handler;
     symbol("let").handler = lambda_handler;
     symbol("=").handler = branch_handler;
     symbol("in");
@@ -150,9 +148,15 @@ var make_parse = function () {
                        var x = symbol(s);
                        x.handler = function () {
                                this.value = symbol_table[this.id].value;
-                               this.arity = "literal";
-                               return this;
+                               if (this.first) {
+                                       return make_app(this.first.handler(), this.value);
+                               } else {
+                                       return this.value;
+                               }
                        };
+                       // constants have their own id and arity = literal
+                       // numbers have id = "(number)" and arity = literal
+                       x.arity = "literal";
                        x.value = v;
                        return x;
                };
@@ -213,7 +217,11 @@ var make_parse = function () {
                     n = token;
                     advance();
                 }
-                if (token.id === ".") {
+                               if (token.arity === "literal" && t.first.length === 0) {
+                                       t.first.push(n);
+                                       t.second = token;
+                                       advance();
+                               } else if (token.id === ".") {
                     t.first.push(n);
                     advance();
                     t.second = expression(in_let);
@@ -249,8 +257,8 @@ var make_parse = function () {
                     n = token;
                     advance(")");
                 } else {
-                    if (token.arity !== "name") {
-                        token.error("Expected a variable name.");
+                    if (token.arity !== "name" && token.arity !== "literal") {
+                        token.error("Expected a variable name or literal.");
                     }
                     token.first = n;
                     n = token;