correct-ish definition of reverse.

src/prolog/ast.rs

@@ -537,7 +537,7 @@ impl fmt::Display for Constant {
             &Constant::Atom(ref atom) =>
                 write!(f, "{}", atom),
             &Constant::Char(c) =>
-                write!(f, "#\\{}", c),
+                write!(f, "{}", c as u8),
             &Constant::EmptyList =>
                 write!(f, "[]"),
             &Constant::Number(ref n) =>

src/prolog/io.rs

@@ -679,6 +679,7 @@ pub fn compile_listing(wam: &mut Machine, src_str: &str) -> EvalSession
                         .or_insert(CodeIndex::default());
 
                     index.0.set(IndexPtr::Index(p));
+                    index.1 = module_name;
                 }
                 
                 decl_info.label_clauses(p, &mut code_dir, &mut decl_code);

src/prolog/machine/machine_state.rs

@@ -426,17 +426,16 @@ pub(crate) trait CallPolicy: Any {
 
                 Ok(())
             },
-            &ClauseType::CallN => {
+            &ClauseType::CallN =>
                 if let Some((name, arity)) = machine_st.setup_call_n(arity) {
                     if let Some(idx) = code_dirs.get(name.clone(), arity, &machine_st.p.clone()) {
-                        return self.context_call(machine_st, name, arity, idx, lco);
+                        self.context_call(machine_st, name, arity, idx, lco)
                     } else {
-                        machine_st.fail = true;
+                        Err(predicate_existence_error(name, arity, machine_st.heap.h))
                     }
-                }
-
-                Ok(())
-            },
+                } else {
+                    Ok(())
+                },
             &ClauseType::Compare => {
                 let a1 = machine_st[temp_v!(1)].clone();
                 let a2 = machine_st[temp_v!(2)].clone();