quote solo characters wherever they lead atoms

src/prolog/machine/machine_indices.rs

@@ -1,3 +1,5 @@
+use indexmap::IndexMap;
+
 use prolog_parser::ast::*;
 use prolog_parser::tabled_rc::*;
 
@@ -412,8 +414,8 @@ impl AddAssign<usize> for CodePtr {
     }
 }
 
-pub type HeapVarDict  = HashMap<Rc<Var>, Addr>;
-pub type AllocVarDict = HashMap<Rc<Var>, VarData>;
+pub type HeapVarDict  = IndexMap<Rc<Var>, Addr>;
+pub type AllocVarDict = IndexMap<Rc<Var>, VarData>;
 
 #[derive(Clone)]
 pub struct DynamicPredicateInfo {

src/prolog/machine/system_calls.rs

@@ -1558,7 +1558,7 @@ impl MachineState {
 
                         let mut list_of_var_eqs = vec![];
 
-                        for (var, binding) in term_write_result.var_dict {
+                        for (var, binding) in term_write_result.var_dict.into_iter().rev() {
                             let var_atom = clause_name!(var.to_string(), indices.atom_tbl);
                             let var_atom = Constant::Atom(var_atom, None);