anchor.diff:          static member        instance (Pure, _:'a Generic.List) = fun x -> new Generic.List<'a>(Seq.singleton x)        
   
           //Restricted
  -        static member instance (Pure, _:'a Nullable  ) = fun (x:'a) -> Nullable x
  +        static member instance (Pure, _:'a Nullable  ) = fun (x:'a  ) -> Nullable x:'a Nullable
  +        static member instance (Pure, _:string       ) = fun (x:char) -> string x : string
  +        static member instance (Pure, _:StringBuilder) = fun (x:char) -> new StringBuilder(string x):StringBuilder
  +        
   
       let inline internal pure' x   = Inline.instance Pure x
   
  
positive.code:         static member instance (Map, x:_ [,,,]       , _) = fun f ->
              Array4D.init (x.GetLength 0) (x.GetLength 1) (x.GetLength 2) (x.GetLength 3) (fun a b c d -> f x.[a,b,c,d])
          static member instance (Map, x:Async<_>      , _) = fun f -> DefaultImpl.MapFromMonad f x
          static member instance (Map, x:Nullable<_>   , _) = fun f -> if x.HasValue then Nullable(f x.Value) else Nullable()
          static member instance (Map, x:Choice<_,_>   , _) = fun f -> Error.map f x
          static member instance (Map, x:Map<'a,'b>    , _) = fun (f:'b->'c) -> Map.map (const' f) x : Map<'a,'c>
          static member instance (Map, x:Expr<_>       , _) = fun f -> <@ f %x @>
          static member instance (Map, x:_ Generic.List, _) = fun f -> new Generic.List<'b>(Seq.map f x)
          
  
      let inline internal fmap   f x = Inline.instance (Map, x) f
  
negative.code: 
  open System
  open System.Collections
  open System.Text
  open Microsoft.FSharp.Quotations
  open FsControl.Core.Prelude
  open FsControl.Core.Types
  