The first xref predicate call generates a textual call graph for the queen module, while the second generates the daVinci graph illustrated in figure 15.1.?- xref:xref(queen, []). nodiag / 3 calls: nodiag / 3 qdelete / 4 calls: qdelete / 4 qperm / 2 calls: qdelete / 4 qperm / 2 queen / 2 calls: qperm / 2 safe / 1 safe / 1 calls: nodiag / 3 safe / 1 Yes (0.01s cpu) ?- xref:xref(queen,[builtins:on,output:daVinci]). WARNING: module 'daVinci' does not exist, loading library... daVinci.ecl compiled traceable 5644 bytes in 0.01 seconds
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Figure 15.1: Call graph for queen example with built-in predicates