anchor.diff:      /// Some magic syntax for composing constant fields.
       static member (?) (_, fieldName) =
           fun (constant : 'c) ->
  -            FieldDefinition.make fieldName typeof<'c> <| Constant constant
  +            FieldDefinition.makeValidated fieldName typeof<'c> <| Constant constant
   
   /// In tandem with the variable literal, grants a nice syntax to define variable fields.
   type DefineVariable =
  
positive.code:     /// Some magic syntax for composing variable fields.
      static member (?) (_, fieldName) =
          fun (variable : unit -> 'v) ->
              FieldDefinition.make fieldName typeof<'v> <| Variable (fun () -> variable () :> obj)
  
  [<AutoOpen>]
  module ReflectionModule =
  
negative.code: [<RequireQualifiedAccess; CompilationRepresentation (CompilationRepresentationFlags.ModuleSuffix)>]
  module FieldDefinition =
  
      /// Validate a field definition.
      let validate fieldDefinition =
          if fieldDefinition.FieldName = "FacetNames" then failwith "FacetNames cannot be an intrinsic field."
          if fieldDefinition.FieldName = "OptOverlayName" then failwith "OptOverlayName cannot be an intrinsic field."
          if Array.exists (fun gta -> gta = typeof<obj>) fieldDefinition.FieldType.GenericTypeArguments then
              failwith <|
                  "Generic field definition lacking type information for field '" + fieldDefinition.FieldName + "'. " +
                  "Use explicit typing on all values that carry incomplete type information such as empty lists, empty sets, and none options,."
  
      /// Make a field definition.
      let make fieldName fieldType fieldExpr =
          { FieldName = fieldName; FieldType = fieldType; FieldExpr = fieldExpr }
  
      /// Make a field definition, validating it in the process.
      let makeValidated fieldName fieldType fieldExpr =
          let result = make fieldName fieldType fieldExpr
          validate result
          result
  
  /// In tandem with the define literal, grants a nice syntax to define constant fields.
  type DefineConstant =
  