diff --git a/core.mal b/core.mal
deleted file mode 100644
index 49bd896..0000000
--- a/core.mal
+++ /dev/null
@@ -1,26 +0,0 @@
-; "not" logic function
-(def! not (fn* (a)
-    (if a false true)))
-
-; binary "or" logic function
-(def! or (fn* (a b)
-    (if a true
-        (if b
-            true
-            false))))
-
-; binary "and" logic function
-(def! and (fn* (a b)
-    (if a
-        (if b
-            true
-            false)
-        false)))
-
-; binary "xor" logic function
-(def! xor (fn* (a b)
-    ; use this strange definition to make it independent from
-    ; "or" and "and" definition
-    (if a
-        (if b false true)
-        (if b true false))))
\ No newline at end of file
diff --git a/src/core.rs b/src/core.rs
index 4e1b281..830c31b 100644
--- a/src/core.rs
+++ b/src/core.rs
@@ -42,10 +42,10 @@ pub fn ns_init() -> Env {
         "*"         => Fun(|a| arithmetic_op(1, |a, b| a * b, a), "Returns the product of the arguments"),
         "/"         => Fun(|a| arithmetic_op(1, |a, b| a / b, a), "Returns the division of the arguments"),
         ">"         => Fun(|a| comparison_op(|a, b| a >  b, a), "Returns true if the arguments are in strictly descending order, 'nil' otherwise"),
-        "<"         => Fun(|a| comparison_op(|a, b| a >  b, a), "Returns true if the arguments are in strictly ascending order, 'nil' otherwise"),
+        "<"         => Fun(|a| comparison_op(|a, b| a <  b, a), "Returns true if the arguments are in strictly ascending order, 'nil' otherwise"),
         ">="        => Fun(|a| comparison_op(|a, b| a >= b, a), "Returns true if the arguments are in descending order, 'nil' otherwise"),
         "<="        => Fun(|a| comparison_op(|a, b| a <= b, a), "Returns true if the arguments are in ascending order, 'nil' otherwise"),
-        "prn"       => Fun(|a| { println!("{} ", prt(car(a)?)); Ok(Nil) }, "Print readably all the arguments"),
+        "prn"       => Fun(|a| {a.iter().for_each(|a| print!("{} ", prt(a))); println!(); Ok(Nil) }, "Print readably all the arguments"),
         "list"      => Fun(|a| Ok(List(MalArgs::new(a.to_vec()))), "Return the arguments as a list"),
         "list?"     => Fun(|a| Ok(Bool(a.iter().all(|el| matches!(el, List(_))))), "Return true if the first argument is a list, false otherwise"),
         "empty?"    => Fun(|a| Ok(Bool(car(a)?.if_list()?.is_empty())), "Return true if the first parameter is an empty list, false otherwise, returns an error if the element is not a list"),
diff --git a/src/env.rs b/src/env.rs
index 6385e71..74cd96c 100644
--- a/src/env.rs
+++ b/src/env.rs
@@ -40,7 +40,9 @@ pub fn env_binds(outer: Env, binds: &MalType, exprs: &[MalType]) -> Result<Env,
     let env = env_new(Some(outer));
     let binds = binds.if_list()?;
     if binds.len() != exprs.len() {
-        return Err(MalErr::unrecoverable("Wrong number of arguments"));
+        return Err(MalErr::unrecoverable(
+            format!("Expected {} args, got {}", binds.len(), exprs.len()).as_str(),
+        ));
     } // TODO: May be possible to leave this be and not set additional elements at all
     for (bind, expr) in binds.iter().zip(exprs.iter()) {
         let bind = bind.if_symbol()?;
@@ -81,24 +83,26 @@ pub fn call_func(func: &MalType, args: &[MalType]) -> MalRet {
 }
 
 pub fn arithmetic_op(set: isize, f: fn(isize, isize) -> isize, args: &[MalType]) -> MalRet {
-    if args.is_empty() {
-        return Ok(M::Int(set));
-    }
-
-    let mut left = args[0].if_number()?;
-    if args.len() > 1 {
-        let right = &args[1..];
-        for el in right {
-            left = f(left, el.if_number()?);
+    Ok(M::Int(match args.len() {
+        0 => set,
+        1 => f(set, args[0].if_number()?),
+        _ => {
+            // TODO: Maybe an accumulator
+            let mut left = args[0].if_number()?;
+            for el in &args[1..] {
+                left = f(left, el.if_number()?);
+            }
+            left
         }
-    }
-
-    Ok(M::Int(left))
+    }))
 }
 
 use MalType::{Bool, Nil};
 
 pub fn comparison_op(f: fn(isize, isize) -> bool, args: &[MalType]) -> MalRet {
+    if args.is_empty() {
+        return Ok(Nil);
+    }
     let (left, rights) = car_cdr(args)?;
     let mut left = left.if_number()?;
     for right in rights {
diff --git a/src/eval.rs b/src/eval.rs
index 3df143c..66222a6 100644
--- a/src/eval.rs
+++ b/src/eval.rs
@@ -193,16 +193,47 @@ mod tests {
         }};
     }
 
+    macro_rules! load_f {
+        ($input:expr, $env:expr) => {{
+            use crate::reader::{read_str, Reader};
+            use std::rc::Rc;
+
+            let r = Reader::new();
+            r.push($input);
+            let args = match read_str(&r) {
+                Ok(v) => match v {
+                    MalType::List(v) => v,
+                    _ => panic!("Bad command"),
+                },
+                _ => panic!("Bad command"),
+            };
+            &MalType::List(Rc::new(if args.is_empty() {
+                Vec::new()
+            } else {
+                let f_str = match &args[0] {
+                    MalType::Sym(s) => s.as_str(),
+                    _ => panic!("Can't solve function"),
+                };
+                let f = match env_get(&$env.clone(), f_str) {
+                    Ok(v) => v,
+                    _ => panic!("No such function in env"),
+                };
+                [&[f], &args[1..]].concat()
+            }))
+        }};
+    }
+
     fn _env_empty() -> Env {
         use crate::env::env_new;
         env_new(None)
     }
 
     mod forms {
-
         use crate::env::env_get;
         use crate::eval::tests::_env_empty;
-        use crate::eval::{def_bang_form, do_form, let_star_form};
+        use crate::eval::{
+            def_bang_form, do_form, eval_ast, eval_func, fn_star_form, if_form, let_star_form,
+        };
         use crate::types::MalType;
 
         #[test]
@@ -271,7 +302,7 @@ mod tests {
         }
 
         #[test]
-        fn _do() {
+        fn _do_form() {
             let env = _env_empty();
             assert!(matches!(
                 do_form(load!("(do)"), env.clone()),
@@ -287,5 +318,83 @@ mod tests {
             ));
             assert!(matches!(env_get(&env.clone(), "a"), Ok(MalType::Int(1))));
         }
+
+        #[test]
+        fn _if_form() {
+            let env = _env_empty();
+            assert!(matches!(
+                if_form(load!("(if)"), env.clone()),
+                Err(e) if !e.is_recoverable()));
+            assert!(matches!(
+                if_form(load!("(if 1)"), env.clone()),
+                Err(e) if !e.is_recoverable()));
+            assert!(matches!(
+                if_form(load!("(if 1 2 3 4)"), env.clone()),
+                Err(e) if !e.is_recoverable()));
+            assert!(matches!(
+                if_form(load!("(if nil 1)"), env.clone()),
+                Ok(MalType::Nil)
+            ));
+            assert!(matches!(
+                if_form(load!("(if nil 1 2)"), env.clone()),
+                Ok(MalType::Int(2))
+            ));
+            assert!(matches!(
+                if_form(load!("(if true 1)"), env.clone()),
+                Ok(MalType::Int(1))
+            ));
+            assert!(matches!(
+                if_form(load!("(if true 1 2)"), env.clone()),
+                Ok(MalType::Int(1))
+            ));
+        }
+
+        #[test]
+        fn fn_star() {
+            let env = _env_empty();
+            assert!(matches!(
+                fn_star_form(load!("(fn* (a b) 1 2)"), env.clone()),
+                Ok(MalType::MalFun { eval, params, ast, .. })
+                if eval == eval_ast
+                && matches!((*params).clone(), MalType::List(v)
+                    if matches!(&v[0], MalType::Sym(v) if v == "a")
+                    && matches!(&v[1], MalType::Sym(v) if v == "b")
+                && matches!((*ast).clone(), MalType::List(v)
+                    if matches!(&v[0], MalType::Int(1))
+                    && matches!(&v[1], MalType::Int(2))))));
+            // We trust the fact that the env does not do silly stuff
+            assert!(matches!(
+                fn_star_form(load!("(fn*)"), env.clone()),
+                Err(e) if !e.is_recoverable()));
+            assert!(matches!(
+                fn_star_form(load!("(fn* 1)"), env.clone()),
+                Err(e) if !e.is_recoverable()));
+        }
+
+        #[test]
+        fn _eval_func() {
+            let env = _env_empty();
+            assert!(matches!(
+                def_bang_form(load!("(def! or (fn* (a b) (if a a b)))"), env.clone()),
+                Ok(_)
+            ));
+            assert!(matches!(
+                eval_func(&MalType::Int(1)),
+                Err(e) if !e.is_recoverable()));
+            assert!(matches!(
+                eval_func(load_f!("()", env.clone())),
+                Err(e) if !e.is_recoverable()));
+            assert!(matches!(
+                eval_func(load_f!("(or nil nil)", env.clone())),
+                Ok(v) if matches!(v, MalType::Nil)));
+            assert!(matches!(
+                eval_func(load_f!("(or 1 nil)", env.clone())),
+                Ok(MalType::Int(1))
+            ));
+            assert!(matches!(
+                eval_func(load_f!("(or nil 1)", env.clone())),
+                Ok(MalType::Int(1))
+            ));
+        }
     }
 }
diff --git a/src/mal_tests/mod.rs b/src/mal_tests/mod.rs
index a896dc6..75bc4bb 100644
--- a/src/mal_tests/mod.rs
+++ b/src/mal_tests/mod.rs
@@ -1,22 +1,14 @@
 #[cfg(test)]
 mod functional {
 
-    macro_rules! load_file {
-        ($file:expr, $env:expr) => {{
-            match load_file($file, $env) {
-                Ok(v) => v,
-                Err(_) => {
-                    panic!()
-                }
-            }
-        }};
-    }
-
     macro_rules! test {
         ($file:expr) => {{
             use crate::core::ns_init;
             use crate::load_file;
-            load_file!(format!("tests/{}.mal", $file).as_str(), &ns_init());
+            assert!(matches!(
+                load_file(format!("tests/{}.mal", $file).as_str(), &ns_init()),
+                Ok(_)
+            ));
         }};
     }
 
@@ -40,6 +32,11 @@ mod functional {
         test!("equals");
     }
 
+    #[test]
+    fn arithmetic() {
+        test!("arithmetic")
+    }
+
     #[test]
     fn fibonacci() {
         test!("fibonacci");
diff --git a/tests/arithmetic.mal b/tests/arithmetic.mal
new file mode 100644
index 0000000..5a38510
--- /dev/null
+++ b/tests/arithmetic.mal
@@ -0,0 +1,51 @@
+; +
+(assert (= (+) 0))
+(assert (= (+ 1) 1))
+(assert (= (+ 1 1) 2))
+(assert (= (+ 1 2 3 4) 10))
+
+; -
+(assert (= (-) 0))
+(assert (= (- 1) -1))
+(assert (= (- 1 2) -1))
+(assert (= (- 10 1 2 3) 4))
+
+; *
+(assert (= (*) 1))
+(assert (= (* 2) 2))
+(assert (= (* 2 3) 6))
+(assert (= (* -2 3) -6))
+(assert (= (* -2 -3) 6))
+(assert (= (* 10 1 2 3) 60))
+
+; /
+(assert (= (/) 1))
+(assert (= (/ 1) 1))
+(assert (= (/ 2) 0))
+(assert (= (/ 3 2) 1))
+(assert (= (/ 128 2 4) 16))
+
+; >
+(assert (not (>)))
+(assert (> 1))
+(assert (> 3 2 1))
+(assert (not (> 3 1 2)))
+(assert (not (> 1 1)))
+; <
+(assert (not (<)))
+(assert (< 1))
+(assert (< 1 2 3))
+(assert (not (< 1 3 2)))
+(assert (not (< 1 1)))
+; >=
+(assert (not (>=)))
+(assert (>= 1))
+(assert (>= 3 2 1))
+(assert (not (>= 3 1 2)))
+(assert (>= 1 1))
+; <=
+(assert (not (<=)))
+(assert (<= 1))
+(assert (<= 1 2 3))
+(assert (not (<= 1 3 2)))
+(assert (<= 1 1))
\ No newline at end of file
diff --git a/tests/lists.mal b/tests/lists.mal
new file mode 100644
index 0000000..39cf24e
--- /dev/null
+++ b/tests/lists.mal
@@ -0,0 +1,9 @@
+; list?
+(assert (list? (list 1 2 3)))
+(assert (not (list? 1)))
+
+; empty?
+(assert (empty? ()))
+(assert (empty? (list)))
+(assert (not (empty? ())))
+(assert (not (empty? (list (1 2 3)))))
\ No newline at end of file