Wire functions through everything, with some unimplemented, and add a basic scoped map.

src/ir/strings.rs

@@ -1,4 +1,4 @@
-use super::ast::{Expression, Program, Statement};
+use super::ast::{Expression, Program, Statement, TopLevel};
 use internment::ArcIntern;
 use std::collections::HashSet;
 
@@ -10,7 +10,7 @@ impl Program {
     pub fn strings(&self) -> HashSet<ArcIntern<String>> {
         let mut result = HashSet::new();
 
-        for stmt in self.statements.iter() {
+        for stmt in self.items.iter() {
             stmt.register_strings(&mut result);
         }
 
@@ -18,6 +18,15 @@ impl Program {
     }
 }
 
+impl TopLevel {
+    fn register_strings(&self, string_set: &mut HashSet<ArcIntern<String>>) {
+        match self {
+            TopLevel::Function(_, _, body) => body.register_strings(string_set),
+            TopLevel::Statement(stmt) => stmt.register_strings(string_set),
+        }
+    }
+}
+
 impl Statement {
     fn register_strings(&self, string_set: &mut HashSet<ArcIntern<String>>) {
         match self {