No. I think the best illustration is the continuation-based Web programming work we did several years ago: http://cs.brown.edu/~sk/Publications/Papers/Published/khmgpf... If you don't have the right underlying language (in this case, with continuations), you _can't_ have a similar API. Similarly, the reactive APIs we had in Flapjax [http://cs.brown.edu/~sk/Publications/Papers/Published/mgbcgb...] enabled entirely new kinds of primitive “library” operations; see, for instance, the drag-and-drop example in that paper.