Algebra.Graph.Labelled.AdjacencyMap.edges appears to be broken

[bgamari]

AdjacencyMap.edges appears not to introduce any edges:

λ> import Algebra.Graph.Labelled.AdjacencyMap
λ> a = AdjMap.edges [((), 'a','b')]
λ> AdjMap.edgeList a
[]
λ> AdjMap.adjacencyMap a
fromList [('a',fromList []),('b',fromList [])]

[bgamari]

Ahh, never mind; I now see that "zero"-annotated (e.g. ()) edges are trimmed from the graph.

[snowleopard]

Yeah, I guess the case with e = () can be pretty confusing since it yields a set rather than a graph.