feat: most basic cli

co-authored by electria

src/main.rs

@@ -1,5 +1,7 @@
+use std::env;
+
 mod parse;
 
 fn main() {
-    println!("Hello, world!");
+    println!("{}", parse::parse(env::args().nth(1).unwrap().as_ref()));
 }

src/parse.rs

@@ -313,6 +313,10 @@ fn nodes_to_num(mut nodes: Vec<Node>) -> Float {
     }
 }
 
+pub fn parse(s: &str) -> Float {
+    nodes_to_num(nodes_from_str(s).unwrap())
+}
+
 #[test]
 fn test_nodes_to_num() {
     assert_eq!(