The GraphMaze library represents mazes using graphs as implemented in the Boost.Graph API.
A maze is represented by an adjacency list, with one vertex per grid cell, beginning in the upper left corner at 0 and increasing along the rows. Edges between vertices represent passages, aka the absence of walls.
A GraphMaze is isomorphic to a regular Maze, and thus this API has typeclass instances of Homomorphism to Maze and Show, which works via the homomorphism to use Show<Maze>.