Fixing some atom functions

core/core.mal

@@ -46,9 +46,11 @@
     (= (count l) 0)))
 
 (def! assert-eq (fn* [a b]
+    "returns an error if arguments are not equals, NIL otherwise"
     (assert (= a b))))
 
 (def! assert-fail (fn* [x]
+    "returns NIL if evaluation of argument fails, error otherwise"
     (assert (not (ok? (eval x))))))
 
 ;; Since thread safety is not required, I will leave it like this,
@@ -58,13 +60,16 @@
 
 ;; File-interaction functions
 (def! load-file (fn* [f]
+    "open a mal file and evaluate its content"
     (eval (read-string (str "(do " (slurp f) "\nnil)")))))
 
 (def! conf-reload (fn* []
+    "reload mal config file"
     (load-file (str MAL_HOME "/" "config.mal"))))
 
 ;; Shorthand
 (def! quit (fn* []
+    "Quit the program with status '0'"
     (exit 0)))
 
 ;; variables
@@ -132,5 +137,3 @@
         "; (help <symbol>)      : print information about a symbol\n"
         ";\n"
         "; enjoy ^.^\n"))
-
-(println BANNER)

src/core.rs

@@ -34,11 +34,22 @@ macro_rules! env_init {
 }
 
 use crate::parse_tools::read_file;
-use crate::printer::pr_str;
+use crate::printer::{pr_str, prt};
 use crate::reader::{read_str, Reader};
 use crate::types::MalType::{Atom, Fun, Int, List, Nil, Str};
 use crate::types::{mal_assert, mal_equals, reset_bang, MalErr};
 
+macro_rules! if_atom {
+    ($val:expr) => {{
+        match $val {
+            Atom(a) => Ok(a.borrow().clone()),
+            _ => Err(MalErr::unrecoverable(
+                format!("{:?} is not an atom", prt($val)).as_str(),
+            )),
+        }
+    }};
+}
+
 pub fn ns_init() -> Env {
     env_init!(None,
         // That's it, you are all going to be simpler functions
@@ -66,9 +77,9 @@ pub fn ns_init() -> Env {
         "assert"        => Fun(mal_assert, "Return an error if assertion fails"),
         "read-string"   => Fun(|a| read_str(Reader::new().push(car(a)?.if_string()?)).map_err(MalErr::severe), "Tokenize and read the first argument"),
         "slurp"         => Fun(|a| Ok(Str(read_file(car(a)?.if_string()?)?)), "Read a file and return the content as a string"),
-        "atom"          => Fun(|a| Ok(Atom(Rc::new(RefCell::new(car(a)?.clone())))), "Return an atom pointing to the given arg"),
-        "deref"         => Fun(|a| match car(a)? { Atom(a) => Ok(a.borrow().clone()), _ => todo!("Cacca suprema") }, "Return the content of the atom argumet"),
-        "reset!"        => Fun(reset_bang, "Set the value of the first argument to the second argument"),
+        "atom"          => Fun(|a| Ok(Atom(Rc::new(RefCell::new(car(a).unwrap_or_default().clone())))), "Return an atom pointing to the given arg"),
+        "deref"         => Fun(|a| if_atom!(car(a)?), "Return the content of the atom argumet"),
+        "reset!"        => Fun(reset_bang, "Change the value of the Atom (frist argument) to the second argument"),
         "env"           => Fun(|a| match env::var(car(a)?.if_string()?) {
             Ok(s) => Ok(Str(s.into())),
             _ => Ok(Nil),

src/env.rs

@@ -103,7 +103,7 @@ pub fn call_func(func: &MalType, args: &[MalType]) -> CallRet {
                         eval(x, inner_env.clone())?;
                     }
                     Ok(CallFunc::MalFun(
-                        list.last().unwrap_or(&Nil).clone(),
+                        list.last().unwrap_or_default().clone(),
                         inner_env,
                     ))
                 }

src/main.rs

@@ -12,7 +12,7 @@ mod step6_file;
 mod types;
 
 use core::ns_init;
-use parse_tools::{interactive, load_file, load_home_file, set_home_path};
+use parse_tools::{interactive, load_file, load_home_file, print_banner, set_home_path};
 
 fn main() {
     // Initialize ns environment
@@ -33,5 +33,7 @@ fn main() {
         }
     });
 
+    print_banner(&reply_env);
+
     interactive(reply_env);
 }

src/parse_tools.rs

@@ -22,6 +22,10 @@ pub fn set_home_path(env: &Env) {
     .unwrap();
 }
 
+pub fn print_banner(env: &Env) {
+    let _ = eval_str("(prn BANNER)", env);
+}
+
 fn get_home_path(env: &Env) -> Result<String, MalErr> {
     Ok(eval_str("MAL_HOME", env)?.if_string()?.to_string())
 }
@@ -92,7 +96,7 @@ pub fn interactive(env: Env) {
             // // Read line to compose program input
             // let mut line = String::new();
             // io::stdin().read_line(&mut line).unwrap();
-            let line = rl.readline("; user> ");
+            let line = rl.readline("; mal> ");
 
             match line {
                 Ok(line) => {

src/step6_file.rs

@@ -4,6 +4,8 @@
 // input, thus this can be referenced by the previous step without the need
 // to allocate more memory
 
+// FIXME: (?) multiple sentences per line, only last is kept
+
 use crate::env::Env;
 use crate::eval::eval;
 use crate::printer::pr_str;

src/types.rs

@@ -29,6 +29,12 @@ pub enum MalType {
     Nil,
 }
 
+impl Default for &MalType {
+    fn default() -> Self {
+        &MalType::Nil
+    }
+}
+
 impl MalType {
     pub fn if_number(&self) -> Result<isize, MalErr> {
         match self {