anchor.diff:                         | Some res -> res
                          | _ ->  failwithf "No default converter registered from R %s " (sexp.Type.ToString())
           
  +    [<Literal>] 
  +    let RDateOffset = 25569.
  +    let createDateVector (dv: seq<DateTime>) = 
  +        let vec = engine.CreateNumericVector [| for x in dv -> x.ToOADate() - RDateOffset |]
  +        vec.SetAttribute("class", engine.CreateCharacterVector [|"Date"|])
  +        vec
  +
       do
           registerToR<SymbolicExpression> (fun engine v -> v)
   
  
positive.code:         registerToR<bool[]>    (fun engine v -> upcast engine.CreateLogicalVector v)
          registerToR<byte[]>    (fun engine v -> upcast engine.CreateRawVector v)
          registerToR<double[]>  (fun engine v -> upcast engine.CreateNumericVector v)
  
          registerToR<string[,]>  (fun engine v -> upcast engine.CreateCharacterMatrix v)
          registerToR<Complex[,]> (fun engine v -> upcast engine.CreateComplexMatrix v)
  
negative.code:         registerToR<bool>    (fun engine v -> upcast engine.CreateLogicalVector [|v|])
          registerToR<byte>    (fun engine v -> upcast engine.CreateRawVector [|v|])
          registerToR<double>  (fun engine v -> upcast engine.CreateNumericVector [|v|])
          registerToR<DateTime> (fun engine v -> upcast createDateVector [|v|])
          
          registerToR<string[]>  (fun engine v -> upcast engine.CreateCharacterVector v)
          registerToR<Complex[]> (fun engine v -> upcast engine.CreateComplexVector v)
  