Get/Set variables from the environment

rust/src/evaluator.rs

@@ -31,12 +31,17 @@ impl<'a> Env<'a> {
             panic!("Variable {} not in scope.", id)
         }
     }
+    pub fn set(&mut self, id: String, atom: Atom) {
+        self.values.insert(id, atom);
+    }
 }
 
 pub fn eval(ast: &parser::Stmt, env: &mut Env) {
     match &ast {
         parser::Stmt::ReplPrint(expr) =>
             println!("{}", eval_expr(expr, env)),
+        parser::Stmt::Assignment(id, expr) =>
+            env.set(id.clone(), eval_expr(expr, env)),
         _ => todo!(),
     }
 }