Sometimes, the graph we're dealing with has a strict structure, such as a hexagonal or square grid. Many video games use a hexagonal grid layout to facilitate diagonal movement because moving diagonally in a square grid complicates the values of the traveled distance. On the other hand, square grid structures are often used within graphs to traverse pixels for image manipulation algorithms such as flood fill.

There is a very useful library in the Haskell package listing to deal with such topologies. We can obtain the indices of a grid to traverse the world, which is essentially a path embedded in a graph. For each grid index, we can query the library to find the neighboring indices, effectively using grids as a graph.

$ cabal install grid