feat: basic string coercion

src/env/core.rs

@@ -300,6 +300,16 @@ pub(super) fn core() -> HashMap<String, Node> {
                 })
             }),
         ),
+        // Strings
+        (
+            "str",
+            Node::NativeFunc(|_env, args| {
+                arg_count!(1, args.len());
+
+                let val = args[0].borrow();
+                Ok(Node::String(val.to_string()))
+            }),
+        ),
         // IO
         (
             "display",

src/evaluator.rs

@@ -156,6 +156,9 @@ mod test {
     #[case("(>= 2 1)", "true")]
     #[case("(>= 1 1)", "true")]
     #[case("(>= 1 2)", "false")]
+    // Strings
+    #[case("(str (+ 1 2))", "3")]
+    #[case("(str (list 1 2 3))", "(1 2 3)")]
     fn test_evaluator(#[case] input: &str, #[case] expected: &str) {
         let env = Environment::new();
         let ast = parser::parse_str(input).unwrap();