add multifile and module scoped predicates

src/prolog/write.rs

@@ -45,6 +45,7 @@ impl fmt::Display for IndexPtr {
             &IndexPtr::DynamicUndefined => write!(f, "undefined"),
             &IndexPtr::Undefined => write!(f, "undefined"),
             &IndexPtr::Index(i) => write!(f, "{}", i),
+            &IndexPtr::InSituDirEntry(i) => write!(f, "in_situ({})", i),
             &IndexPtr::UserTermExpansion => write!(f, "user:term_expansion"),
             &IndexPtr::UserGoalExpansion => write!(f, "user:goal_expansion"),
         }
@@ -261,8 +262,14 @@ impl fmt::Display for SessionError {
                 write!(f, "filename {} is invalid", filename)
             }
             &SessionError::ModuleNotFound => write!(f, "module not found."),
-            &SessionError::ModuleDoesNotContainExport => {
-                write!(f, "module does not contain claimed export.")
+            &SessionError::ModuleDoesNotContainExport(ref module, ref key) => {
+                write!(
+                    f,
+                    "module {} does not contain claimed export {}/{}",
+                    module,
+                    key.0,
+                    key.1,
+                )
             }
             &SessionError::OpIsInfixAndPostFix(_) => {
                 write!(f, "cannot define an op to be both postfix and infix.")