fix function calls with no argument

src/eval.rs

@@ -46,14 +46,22 @@ pub fn eval(
 
     // another check to detect if we may have a function call
     if let Ctr::Symbol(ref tok) = car {
-        if let Ctr::Seg(ast) = cdr {
+        match cdr {
+            Ctr::Seg(ast) => {
                 if let Some(func) = funcs.borrow().get(tok) {
                     return func_call(func.clone(), ast.clone(), vars.clone(), funcs.clone())
                 } else {
                     return Err(format!("Couldnt find function: {}.", tok))
                 }
+            },
+            Ctr::None => {
+                if let Some(func) = funcs.borrow().get(tok) {
+                    return func_call(func.clone(), new_ast(Ctr::None, Ctr::None), vars.clone(), funcs.clone())
                 } else {
-            return Err(format!("Arguments to function not a list!"))
+                    return Err(format!("Couldnt find function: {}.", tok))
+                }
+            },
+            _ => return Err(format!("Arguments to function not a list!"))
         }
     }