Added pointer for outer environment

Signed-off-by: teo3300 <matteo.rogora@live.it>

src/envs.rs

@@ -5,12 +5,14 @@ use crate::types::{int_op, MalArgs, MalRet, MalType};
 
 pub struct Env {
     map: HashMap<String, MalType>,
+    outer: Option<Box<Env>>,
 }
 
 impl Env {
-    pub fn new() -> Self {
+    pub fn new(outer: Option<Box<Env>>) -> Self {
         let mut env = Env {
             map: HashMap::new(),
+            outer,
         };
         env.init();
         env

src/main.rs

@@ -14,7 +14,7 @@ use step2_eval::rep;
 
 fn main() {
     let mut num = 0;
-    let env = Env::new();
+    let env = Env::new(None);
 
     loop {
         let mut input = String::new();

src/mal_core.rs

@@ -5,7 +5,7 @@ use crate::types::{MalArgs, MalRet, MalType};
 fn call_func(func: &MalType, args: MalArgs) -> MalRet {
     match func {
         Fun(func) => func(args),
-        _ => panic!("Calling not a function"),
+        _ => Err(format!("{:?} is not a function", func)),
     }
 }
 
@@ -28,8 +28,8 @@ pub fn eval(ast: MalType, env: &Env) -> MalRet {
     match &ast {
         List(list) => {
             if list.is_empty() {
-                Ok(Nil)
-                // Previously Ok(ast)
+                // Ok(Nil) // Should be the normal behavior
+                Ok(ast)
             } else {
                 eval_func(eval_ast(ast, env)?)
             }

src/printer.rs

@@ -6,7 +6,7 @@ pub fn pr_str(ast: &MalType, print_readably: bool) -> String {
     match ast {
         Nil => "nil".to_string(),
         Sym(sym) => sym.to_string(),
-        Key(sym) => sym[1..sym.len() - 1].to_string(),
+        Key(sym) => sym[2..].to_string(),
         Int(val) => val.to_string(),
         Bool(val) => val.to_string(),
         Str(str) => {

src/types.rs

@@ -31,7 +31,7 @@ pub type MalErr = String;
 pub type MalArgs = Vec<MalType>;
 pub type MalRet = Result<MalType, MalErr>;
 
-use MalType::{Key, Map, Str, Sym};
+use MalType::{Key, Map, Str};
 
 pub fn make_map(list: MalArgs) -> MalRet {
     if list.len() % 2 != 0 {
@@ -42,7 +42,7 @@ pub fn make_map(list: MalArgs) -> MalRet {
 
     for i in (0..list.len()).step_by(2) {
         match &list[i] {
-            Sym(k) | Key(k) | Str(k) => {
+            Key(k) | Str(k) => {
                 let v = list[i + 1].clone();
                 map.insert(k.clone(), v);
             }