anchor.diff:  open Starling.Core.Command
   open Starling.Core.GuardedView
   open Starling.Core.Symbolic
  +open Starling.Core.TypeSystem
   open Starling.TermGen.Iter
   
   [<AutoOpen>]
  
positive.code:         | InductiveDownclosureError of view : DView * def : BoolExpr<Sym<Var>>
          /// <summary>
          ///     An iterated view definition failed the base downclosure
          ///     property.
          ///
          ///     <para>
          ///         This is the property that a view definition, when
  
negative.code:                     printDFunc
                      (Option.map printTypedVar >> withDefault Nop)
                      func ]
          | BadIteratorType (view, ty) ->
              fmt "iterator on constraint '{0}' is of type {1}, should be int"
                  [ printDView view
                    printType ty ]
          | MissingIterator view ->
              fmt "constraint '{0}' should have an iterator, but does not"
                  [ printDView view ]
          | SymInIteratedConstraint sym ->
              fmt "symbol '{0}' not allowed in an iterated constraint"
                  [ String sym ]
          >> error
  