expr to sexpr (unfinished)

example/ex.hyc

@@ -1,12 +1 @@
-fun foo a b = a * b;
-let bar = foo( 3 3 );
-let baz = bar in print(baz);
-
-if bar == 9 then
-    do
-        print(bar);
-        print(":)");
-    end
-else
-    print(":(");
-end;
+let foo = 1 + 1 in 2 + foo;

src/front/parse.rs

@@ -312,3 +312,33 @@ pub fn parser() -> impl Parser<Token, Vec<Expr>, Error = Simple<Token>> + Clone
         .repeated()
         .then_ignore(end())
 }
+
+impl Expr {
+    pub fn to_sexpr(&self) -> String {
+        let mut out = String::new();
+        match self {
+            Self::Int(x)     => out.push_str(&x.to_string()),
+            Self::Float(x)   => out.push_str(&x.to_string()),
+            Self::Boolean(x) => out.push_str(&x.to_string()),
+            Self::String(x)  => out.push_str(&format!("\"{}\"", x)),
+            Self::Ident(x)   => out.push_str(&x),
+
+            Self::Unary{ op, expr }         => out.push_str(&format!("({} {})", op, expr.to_sexpr())),
+            Self::Binary{ op, left, right } => out.push_str(
+                &format!("({} {} {})", op, left.to_sexpr(), right.to_sexpr())
+            ),
+
+            Self::Let{ name, value, then } => {
+                let then = match *then.clone() {
+                    Some(v) => format!("\n  (do {})", v.to_sexpr()),
+                    None => "".to_string(),
+                };
+                out.push_str(&format!("(let\n  {}\n  {}{})", name, value.clone().to_sexpr(), then))
+            },
+
+            // TODO: finish the rest of the Expr, I'm going to sleep, goodnight.
+            _ => todo!(), 
+        }
+        out
+    }
+}

src/main.rs

@@ -22,7 +22,12 @@ fn main() {
             let (ast, parse_error) = parser().parse_recovery(Stream::from_iter(len..len + 1, tokens.clone().unwrap().into_iter()));
             if lex_error.is_empty() {
                 if parse_error.is_empty() {
-                    println!("{:#?}", ast);
+                    match ast {
+                        Some(ast) => {
+                            println!("{}", ast.iter().map(|e| e.to_sexpr()).collect::<String>())
+                        },
+                        None => println!("no ast :("),
+                    };
                 } else {
                     eprintln!("{:#?}\n(Parser error)", parse_error);
                 }