;;;; Copyright (c) 2015, Jeremy Steward
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;; NOTE This file holds some generic helpers and utilities for the graphs-derived
;; module. Do not confuse this with src/utils.scm!!!

(define (num-adjacencies G u v)
    @("Calculates the number of adjacencies (edges) between vertices u and v"
      (G "the graph to count adjacencies in")
      (u "The head vertex")
      (v "The tail vertex")
      (@to "integer")
      (@no-source))
    (set-count (set-filter (lambda (x)
                             (equal? (if (multigraph? G) (car x) x)
                                     v))
                           (graph-neighbours G u))))