On 28 April 2012 11:38, Felipe Almeida Lessa <felipe.le...@gmail.com> wrote: > Hello! > > I'm sorry if this is a dumb question, I was just reading the API docs, > but: what happens if one by one I add all edges of a non-planar graph > using addEdge? Are there any sanity checks that would tell me "sorry, > but your graph isn't planar", or would it just give me wrong answers?
Wrong answers. I'm assuming you have *some* intelligence :p The original plans were to have Maybe variants that would perform such sanity checks, but as I was going for performance (as my supervisor is of the opinion that if it isn't C it isn't worth considering for pure performance reasons) the default versions didn't include them, and it slipped my mind until you just reminded me :) I can add them in if anyone wants them: what it entails is to add the edge and then perform planarity testing [3]; this can get expensive if the graph is large (I did once work out an approach that involved just checking the new face[s], but I don't recall what it was or whether it was correct). [3]: http://en.wikipedia.org/wiki/Planarity_testing (My rationale for this library was to implement a graph-generating algorithm; I knew what the ordering was, so I didn't need any "will adding this keep it planar" checks.) -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com http://IvanMiljenovic.wordpress.com _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
