start enabling the dynamic database

src/prolog/machine/machine_errors.rs

@@ -25,6 +25,13 @@ impl MachineError {
         functor!("/", 2, [name, heap_integer!(arity)], (400, YFX))
     }
 
+    pub(super) fn static_modification_error(perm_error: PermissionError, culprit: Addr) -> Self {
+        let stub = functor!("permission_error", 3, [heap_atom!(perm_error.as_str()),
+                                                    heap_atom!("static_procedure"),
+                                                    HeapCellValue::Addr(culprit)]);
+        MachineError { stub, from: ErrorProvenance::Received }
+    }
+
     pub(super) fn evaluation_error(eval_error: EvalError) -> Self {
         let stub = functor!("evaluation_error", 1, [heap_atom!(eval_error.as_str())]);
         MachineError { stub, from: ErrorProvenance::Received }
@@ -153,6 +160,19 @@ impl ValidType {
     }
 }
 
+#[derive(Clone, Copy)]
+pub enum PermissionError {
+    Modify
+}
+
+impl PermissionError {
+    pub fn as_str(self) -> &'static str {
+        match self {
+            PermissionError::Modify => "modify"
+        }
+    }
+}
+
 #[derive(Clone, Copy)]
 pub enum DomainError {
     NotLessThanZero