repos/tabletprog: interp.js comparison

comparison interp.js @ 221:218b11ec8fa2

Better handling for weird values being inserted into AST due to quoting

author	Michael Pavone <pavone@retrodev.com>
date	Sun, 29 Dec 2013 13:07:10 -0800
parents	b70be565d54c
children	97c3e33cd3f4

comparison

equal deleted inserted replaced

-:a1a80af71b05
+:218b11ec8fa2
 		return new symbol('true');
 	}
 	if (val == tpfalse) {
 		return new symbol('false');
 	}
-	return val;
+	if ('makeHygienic' in val) {
+		return val;
+	}
+	return null;
 }
 op.prototype.eval = function(env) {
 	var l = this.left.eval(env);
 	var name = this.op;
 symbol.prototype.quote = function(env) {
 	var val = env.find(this.name);
 	if (val !== null) {
 		var newnode = makeASTNode(val);
+		if (!newnode) {
+			throw new Error(this.name + ' contains a value ' + val + ' that could not be converted to an AST node');
+		}
 		return newnode;
 	} else {
 		this.dirty = true;
 		return this;
 	}
 	var val = env.find(name);
 	var dirty = true;
 	if (val) {
 		var node = makeASTNode(val);
 		if (!(node instanceof symbol)) {
-			throw new Error('Left hand side of assignment expression must be a symbol!');
+			throw new Error('Left hand side of assignment expression must be a symbol not a '+ node.constructor.name + ' '+(typeof node) + ', old name was ' + name);
 		}
 		name = node.cleanName();
 		dirty = node.dirty;
 	}
 	env.syms[name] = null;