From 9841143d0c5ce040b303b484c474528034919a16 Mon Sep 17 00:00:00 2001
From: Edward Amsden <edward@blackriversoft.com>
Date: Thu, 8 Aug 2024 10:20:56 -0500
Subject: [PATCH] Make noun::Error an instance of std::error::Error

---
 rust/ares/src/noun.rs | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/rust/ares/src/noun.rs b/rust/ares/src/noun.rs
index 3ce5f80..1e2489f 100644
--- a/rust/ares/src/noun.rs
+++ b/rust/ares/src/noun.rs
@@ -4,6 +4,7 @@ use bitvec::prelude::{BitSlice, Lsb0};
 use either::{Either, Left, Right};
 use ibig::{Stack, UBig};
 use intmap::IntMap;
+use std::error;
 use std::fmt;
 use std::ptr;
 use std::slice::{from_raw_parts, from_raw_parts_mut};
@@ -172,6 +173,21 @@ pub enum Error {
     NotRepresentable,
 }
 
+impl error::Error for Error {}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Error::NotAllocated => f.write_str("not an allocated noun"),
+            Error::NotAtom => f.write_str("not an atom"),
+            Error::NotCell => f.write_str("not a cell"),
+            Error::NotDirectAtom => f.write_str("not a direct atom"),
+            Error::NotIndirectAtom => f.write_str("not an indirect atom"),
+            Error::NotRepresentable => f.write_str("unrepresentable value"),
+        }
+    }
+}
+
 impl From<Error> for () {
     fn from(_: Error) -> Self {}
 }