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

src/ir/eval.rs

@@ -1,5 +1,5 @@
 use crate::eval::{EvalEnvironment, EvalError, Value};
-use crate::ir::{Expression, Program, Statement};
+use crate::ir::{Expression, Program, Statement, TopLevel};
 
 use super::{Primitive, Type, ValueOrRef};
 
@@ -12,14 +12,16 @@ impl Program {
         let mut env = EvalEnvironment::empty();
         let mut stdout = String::new();
 
-        for stmt in self.statements.iter() {
+        for stmt in self.items.iter() {
             match stmt {
-                Statement::Binding(_, name, _, value) => {
+                TopLevel::Function(_, _, _) => unimplemented!(),
+
+                TopLevel::Statement(Statement::Binding(_, name, _, value)) => {
                     let actual_value = value.eval(&env)?;
                     env = env.extend(name.clone(), actual_value);
                 }
 
-                Statement::Print(_, _, name) => {
+                TopLevel::Statement(Statement::Print(_, _, name)) => {
                     let value = env.lookup(name.clone())?;
                     let line = format!("{} = {}\n", name, value);
                     stdout.push_str(&line);