The standard library graph_by_edge_hashtable package implements a graph representation which uses hashtables to yield O(1) tests for existence of an edge in the graph. At present it is used mainly in the compiler.
The graph_by_edge_hashtable package implements the Graph_By_Edge_Hashtable API.
The graph_by_edge_hashtable package source code is in src/lib/std/src/graph-by-edge-hashtable.pkg.
The above information is manually maintained and may contain errors.