1 files changed, 25 insertions, 0 deletions
diff --git a/dhall_syntax/src/core/visitor.rs b/dhall_syntax/src/core/visitor.rs
index 1745fdb..b02544f 100644
--- a/dhall_syntax/src/core/visitor.rs
+++ b/dhall_syntax/src/core/visitor.rs
@@ -358,6 +358,31 @@ where
     }
 }
 
+pub struct ResolveVisitor<F1>(pub F1);
+
+impl<'a, 'b, N, E, E2, Err, F1>
+    ExprFFallibleVisitor<'a, SubExpr<N, E>, SubExpr<N, E2>, E, E2>
+    for &'b mut ResolveVisitor<F1>
+where
+    N: Clone + 'a,
+    F1: FnMut(&E) -> Result<E2, Err>,
+{
+    type Error = Err;
+
+    fn visit_subexpr(
+        &mut self,
+        subexpr: &'a SubExpr<N, E>,
+    ) -> Result<SubExpr<N, E2>, Self::Error> {
+        Ok(subexpr.rewrap(
+            subexpr
+                .as_ref()
+                .traverse_resolve_with_visitor(&mut **self)?,
+        ))
+    }
+    fn visit_embed(self, embed: &'a E) -> Result<E2, Self::Error> {
+        (self.0)(embed)
+    }
+}
 pub struct NoteAbsurdVisitor;
 
 impl<'a, 'b, N, E>