Apply GRAFTS to the OUTPUTS of DRV and all their dependencies, recursively. That is, if GRAFTS apply only indirectly to DRV, graft the dependencies of DRV, and graft DRV itself to refer to those grafted dependencies.

Return the graph backend called NAME. Raise an error if it is not found.

Return as a monadic value the shortest path, represented as a list, from NODE1 to NODE2 of the given TYPE. Return #f when there is no path.

Return the number of nodes reachable from NODES along NODE-EDGES.

Return, as a monadic value, a one-argument procedure that, given a node of TYPE, returns its back edges. NODES is taken to be the sinks of the global graph.