existing-records.md

@@ -119,3 +119,16 @@ f x = ... where
 
 
 open x would be allowed at the top level, in a let binding, or in a where binding.
+
+## abstraction
+
+
+It is often useful to limit the ability of users to fill in or access parts of a data type arbitrarily to maintain invariants, instituting the following rule would let you enforce that to some degree:
+
+- Positional notation for pattern matching and constructor creation for a constructor may not be used unless all of its field labels are in scope.
+
+
+This would insure that by not exporting a field label, it cannot be gotten around by using positional notation.
+
+
+this fix would also require the polymorphic setting ability mentioned above and would partially mitigate the need for [ReadonlyConstructors](readonly-constructors)
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