Closure (#1)

* Add 'closures' and sample programs, lodash too

* Remove prettier garbage

1 files changed, 23 insertions, 1 deletions

diff --git a/static/js/lang.js b/static/js/lang.js
index 50fe098..92ff133 100644
--- a/static/js/lang.js
+++ b/static/js/lang.js
@@ -565,6 +565,18 @@ class Environment {
         }
         return rv;
     }
+    addClosure(node, closure) {
+        if (Array.isArray(node)) {
+            for (let i = 0; i < node.length; ++i)
+                node[i] = this.addClosure(node[i], closure);
+        } else if (typeof node === "object") {
+            for (let key of Object.keys(node).filter((key) => key != "closure")) {
+                node[key] = this.addClosure(node[key], closure);
+                node.closure = closure;
+            }
+        }
+        return node;
+    }
     eval(node) {
         const scope = this.scopes[this.scopes.length - 1];
 
@@ -574,7 +586,10 @@ class Environment {
             case N.BoolLiteral:
                 return node.val;
             case N.FnDecl: {
-                scope[node.name] = node;
+                node.closure = _.cloneDeep({ ...node.closure, ...scope });
+                node.body = this.addClosure(node.body, node.closure);
+
+                scope[node.name] = _.cloneDeep(node);
                 return node;
             }
             case N.FnCall: {
@@ -610,6 +625,13 @@ class Environment {
                     }
                     i --;
                 }
+								if (node.closure && node.closure.hasOwnProperty(node.val)) {
+										const val = node.closure[node.val];
+										if (typeof val === "object") {
+												return this.eval(val);
+										}
+										return val;
+								}
                 throw new Error(`Runtime error: Undefined variable "${node.val}"`);
             }
             case N.Assignment: {