Change loom.alg-generic/pre-traverse to do much less work#120
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Change loom.alg-generic/pre-traverse to do much less work#120jafingerhut wants to merge 1 commit into
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especially if the graph is dense with edges for a node that is traversed, but the returned lazy sequence is not ever evaluated to get to those nodes. Also eliminate a stack-growing recursive call, using recur instead. The previous version could grow the call stack nearly as deep as the number of edges in the graph.
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I was using pre-traverse to do a partial DFS of some large graphs where some nodes had very high degree, and found that it was doing a lot of unnecessary work for edges in the graph that were never 'crossed' by my partial DFS. |
jsavyasachi
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Jun 21, 2026
Walk each node's successors one at a time, remembering the position on the stack, instead of eagerly pushing every unseen neighbor. Avoids O(E) stack growth on dense graphs; preorder is unchanged. Closes aysylu#120.
jsavyasachi
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Adds simple-paths (aysylu#111) and digraph-all-cycles (aysylu#126); perf for degeneracy-ordering (aysylu#108) and pre-traverse (aysylu#120).
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especially if the graph is dense with edges for a node that is
traversed, but the returned lazy sequence is not ever evaluated to get
to those nodes.
Also eliminate a stack-growing recursive call, using recur instead.
The previous version could grow the call stack nearly as deep as the
number of edges in the graph.