1 files changed, 17 insertions, 3 deletions

diff --git a/src/lisp/error.rs b/src/lisp/error.rs
index 4f90d14..b90e211 100644
--- a/src/lisp/error.rs
+++ b/src/lisp/error.rs
@@ -1,4 +1,7 @@
-use crate::lisp::lex::{Span, SpanDisplay};
+use crate::lisp::{
+    expr::Arity,
+    lex::{Span, SpanDisplay},
+};
 
 use std::fmt;
 
@@ -81,23 +84,34 @@ impl From<ParseError> for LispError {
 
 #[derive(Debug, PartialEq, Clone)]
 pub enum EvalError {
-    ArgumentCount(Option<u32>), // expected
+    ArgumentCount(Arity),
     BadForm,
     UnboundVariable(String),
     DivByZero,
     TypeMismatch,
+    NoFileName,
 }
 
 impl fmt::Display for EvalError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
             Self::ArgumentCount(i) => {
-                write!(f, "invalid number of arguments, expected atleast {:?}", i)
+                write!(f, "invalid number of arguments, expected ")?;
+                match i {
+                    Arity::Exact(a) => write!(f, "exactly {} argument(s)", a),
+                    Arity::Atleast(a) => write!(f, "atleast {} argument(s)", a),
+                    Arity::Atmost(a) => write!(f, "atmost {} argument(s)", a),
+                    Arity::Range(low, high) => {
+                        write!(f, "between {} and {} argument(s)", low, high)
+                    }
+                    Arity::None => write!(f, "any number of arguments"),
+                }
             }
             Self::BadForm => write!(f, "bad expression form"),
             Self::UnboundVariable(s) => write!(f, "unbound variable {}", s),
             Self::TypeMismatch => write!(f, "mismatched types"),
             Self::DivByZero => write!(f, "attempt to divide by zero"),
+            Self::NoFileName => write!(f, "no file name specified"),
         }
     }
 }