[Haskell-cafe] FGL: The cost and propoer way of changing the label at a node.

Is changing the label at a node O(N)? The only way I can think of to do it is with a map, like the following -- which works, but seems like its speed must be linear in the number of nodes of the graph:

:m Data.Graph.Inductive.Example Data.Graph.Inductive.Graph let f c@(adjIn, node, lab, adjOut) = case node of {1 -> (adjIn, node, 'b', adjOut); _ -> c} loop mkGraph [(1,'a')] [(1,1,())] gmap f loop mkGraph [(1,'b')] [(1,1,())]

Is that in fact the right way? Am I somehow missing the point of FGL if I have to do a lot of that?