adamc@697: datatype lines = End | Line of string * source lines
adamc@697: 
adamc@697: type t = { Head : source lines, Tail : source (source lines) }
adamc@697: 
adamc@697: val create =
adamc@697:     head <- source End;
adamc@697:     tail <- source head;
adamc@697:     return {Head = head, Tail = tail}
adamc@697: 
adamc@697: fun renderL lines =
adamc@697:     case lines of
adamc@697:         End => <xml/>
adamc@697:       | Line (line, linesS) => <xml>{[line]}<br/><dyn signal={renderS linesS}/></xml>
adamc@697: 
adamc@697: and renderS linesS =
adamc@697:     lines <- signal linesS;
adamc@697:     return (renderL lines)
adamc@697: 
adamc@697: fun render t = renderS t.Head
adamc@697: 
adamc@697: fun write t s =
adamc@697:     oldTail <- get t.Tail;
adamc@697:     newTail <- source End;
adamc@697:     set oldTail (Line (s, newTail));
adamc@697:     set t.Tail newTail