simplify detecting undefined goal_ and term_expansion

src/loader.pl

@@ -34,23 +34,13 @@ write_error(Error) :-
     write('.').
 
 '$print_message_and_fail'(Error) :-
-    (  (  Error = error(existence_error(procedure, Expansion), Expansion)
-       ;  Error = error(evaluation_error((_:_)/_),Expansion)
-       )  ->
-       (  (  Expansion = goal_expansion/2
-          ;  Expansion = term_expansion/2
-          )  ->
-          true
-       ;  write_error(Error),
-          nl
-       )
-    ;  write_error(Error),
-       nl
-    ),
+    write_error(Error),
+    nl,
     '$fail'.
 
 expand_term(Term, ExpandedTerm) :-
-    (  catch('$call'(user:term_expansion(Term, ExpandedTerm0)),
+    (  '$predicate_defined'(user, term_expansion, 2),
+       catch('$call'(user:term_expansion(Term, ExpandedTerm0)),
              E,
              '$call'(loader:'$print_message_and_fail'(E))) ->
        (  var(ExpandedTerm0) ->
@@ -77,6 +67,7 @@ term_expansion_list([Term|Terms], ExpandedTermsHead, ExpandedTermsTail) :-
 
 goal_expansion(Goal, Module, ExpandedGoal) :-
     (  atom(Module),
+       '$predicate_defined'(Module, goal_expansion, 2),
        catch('$call'(Module:goal_expansion(Goal, ExpandedGoal0)),
              E,
              '$call'(loader:'$print_message_and_fail'(E))) ->

src/machine/dispatch.rs

@@ -4851,6 +4851,14 @@ impl Machine {
                     try_or_throw!(self.machine_st, self.add_non_counted_backtracking());
                     self.machine_st.p = self.machine_st.cp;
                 }
+                &Instruction::CallPredicateDefined(_) => {
+                    self.machine_st.fail = !self.predicate_defined();
+                    self.machine_st.p += 1;
+                }
+                &Instruction::ExecutePredicateDefined(_) => {
+                    self.machine_st.fail = !self.predicate_defined();
+                    self.machine_st.p = self.machine_st.cp;
+                }
             }
         }
 

src/machine/system_calls.rs

@@ -3771,6 +3771,39 @@ impl Machine {
         self.machine_st.fail = !self.indices.modules.contains_key(&module_name);
     }
 
+    pub(crate) fn predicate_defined(&self) -> bool {
+        let module_name = cell_as_atom!(self.machine_st.store(self.machine_st.deref(
+            self.machine_st.registers[1]
+        )));
+
+        let name = cell_as_atom!(self.machine_st.store(self.machine_st.deref(
+            self.machine_st.registers[2]
+        )));
+
+        let arity = match Number::try_from(self.machine_st.store(self.machine_st.deref(
+            self.machine_st.registers[3]
+        ))) {
+            Ok(Number::Fixnum(n))  => n.get_num() as usize,
+            Ok(Number::Integer(n)) => {
+                if let Some(n) = n.to_usize() {
+                    n
+                } else {
+                    return false;
+                }
+            }
+            _ => {
+                unreachable!()
+            }
+        };
+
+        self.indices.get_predicate_code_index(
+            name,
+            arity,
+            module_name,
+        ).map(|index| index.local().is_some())
+         .unwrap_or(false)
+    }
+
     #[inline(always)]
     pub(crate) fn no_such_predicate(&mut self) -> CallResult {
         let module_name = cell_as_atom!(self.machine_st.store(self.machine_st.deref(