Fix variable lookup

2016-01-22 02:59:33 -08:00 · 2016-01-22 02:59:33 -08:00 · b1f9e5cefc
commit b1f9e5cefc
parent be36d4697d
1 changed files with 4 additions and 2 deletions
--- a/src/eval.rs
+++ b/src/eval.rs
@ -101,8 +101,10 @@ impl Evaluator {
            e@StringLiteral(_) => e,
            e@Number(_) => e,
            Variable(var) => {
-                let expr = self.varmap.lookup_binding(var).unwrap();
-                expr.clone()
+                match self.varmap.lookup_binding(var) {
+                    None => Null,
+                    Some(expr) => expr.clone()
+                }
            },
            BinExp(op, box left, box right) => {
                if right.is_reducible() {