Am 16.12.2012 20:24, schrieb Jason Dagit:
How does this compare with fgl? http://hackage.haskell.org/package/fgl
FGL is a pure Haskell library while our haskell-igraph package uses the foreign function interface to run all graph-related calculations in C the C library igraph (I haven't implemented any graph algorithms). The runtime performance with our igraph library should be the same as if you'd be using the native C library (if you ignore the small Haskell->C->Haskell overhead). It is also seems to be more of a higher level library. As user you don't have to worry about node-IDs/labels or whether your graph is "static" or not (in the FGL context). Using features like GADTs and type families/associated types it is possible to keep track of informations like whether or not your graph is directed/weighted or not, while in FGL all graphs are by default directed and unweighted. Consider for example edges :: Graph d a -> [Edge d a] -- directed, unweighted graph g :: Graph D a -- undirected, weighted graph w :: Graph (Weighted U) a which leads to edges g :: [Edge D a] edges w :: [Edge (Weighted U) a] or even functions like toUndirected :: (IsDirected d, E (ToUndirected d) a) => Graph d a -> Graph (ToUndirected d) a toDirected :: (IsUndirected u, E (ToDirected u) a) => Graph u a -> Graph (ToDirected u) a which evaluate to toUndirected g :: Graph U a toDirected w :: Graph (Weighted D) a This is even revertable, and `toDirected . toUndirected == id` while the FGL function `undir` simply adds all missing edges and loses track of what the original/directed graph looked like. Maybe George has more details on why he wanted to use igraph instead of FGL. - Nils