anchor.diff:        doc
   
     let outputToWriter (tw: TextWriter) maxCols doc =
  -    outputWithFun (fun s -> tw.Write s) maxCols doc
  +    outputWithFun tw.Write maxCols doc
   
     let render maxCols doc =
       use tw = new StringWriter ()
  
positive.code:     tw.ToString ()
  
    let println maxCols doc =
      outputWithFun (fun s -> Console.Write s) maxCols doc
      Console.Write "\n"
  
negative.code:          layout (force doc)
  
      let fits usedCols doc =
        match maxCols with
         | None -> true
         | Some maxCols ->
           let rec lp usedCols doc =
             usedCols <= maxCols &&
             match force doc with
              | NIL | LINEFEED _ -> true
              | OBJ (_, doc) -> lp usedCols doc
              | PRINT (str, doc) -> lp (usedCols + String.length str) doc
           lp usedCols (lazy doc)
  
      let rec best usedCols = function
        | [] -> NIL
  