Clojurians Log v2

thanks, I think I understand scan a little better now. Played around a bit more and ended up with:

(defn xml->tracks
  [xml]
  (m/search
   xml
   {:tag ::tx/tfmDataService
    :content ({:tag ::tx/fltdOutput
               :content (m/scan
                         {:tag ::fdm/fltdMessage
                          :attrs {:msgType "trackInformation"
                                  :flightRef ?flight-ref
                                  :acid ?aircraft-id
                                  :airline ?airline
                                  :depArpt ?departure-airport
                                  :arrArpt ?arrival-airport
                                  :sourceTimeStamp ?message-ts}
                          :content ({:tag ::fdm/trackInformation
                                     :content (m/scan
                                               {:tag ::nxcm/qualifiedAircraftId}
                                               {:tag ::nxcm/speed
                                                :content (?speed)}
                                               {:tag ::nxcm/reportedAltitude
                                                :content ({:tag ::nxce/assignedAltitude
                                                           :content ((m/or
                                                                      {:tag ::nxce/simpleAltitude
                                                                       :content (?altitude)}
                                                                      {:tag ::nxce/blockedAltitude
                                                                       :attrs {:min (?altitude)}}
                                                                      {:tag ::nxce/visualFlightRules
                                                                       :attrs {:altitude ?altitude}}
                                                                      {:tag ::nxce/altitudeFixAltitude
                                                                       :attrs {:preFixAltitude ?altitude}}))})}
                                               {:tag ::nxcm/position
                                                :content (m/scan
                                                          {:tag ::nxce/latitude
                                                           :content ({:tag ::nxce/latitudeDMS
                                                                      :attrs ?latitude-dms})}
                                                          {:tag ::nxce/longitude
                                                           :content ({:tag ::nxce/longitudeDMS
                                                                      :attrs ?longitude-dms})})}
                                               {:tag ::nxcm/timeAtPosition
                                                :content (?track-ts)}
                                               .
                                               (m/or
                                                {:tag ::nxcm/ncsmTrackData
                                                 :content (m/seqable
                                                           .
                                                           (m/or
                                                            {:tag ::nxcm/nextEvent
                                                             :attrs {:latitudeDecimal ?next-lat
                                                                     :longitudeDecimal ?next-long}}
                                                            (m/let [?next-lat nil ?next-long nil]))
                                                           ..1)}
                                                {:tag ::nxcm/ncsmRouteData
                                                 :content (m/scan
                                                           {:tag ::nxcm/nextPosition
                                                            :attrs {:latitudeDecimal ?next-lat
                                                                    :longitudeDecimal ?next-long}})}))})})})}
   (merge {:flight/ref (Long/parseLong ?flight-ref)
           :flight/aircraft-id ?aircraft-id
           :flight/airline ?airline
           :flight/arrival-airport ?arrival-airport
           :flight/departure-airport ?departure-airport
           :track/speed (Integer/parseInt ?speed)}
          (when (and ?next-lat ?next-long)
            {:track/next-latitude (Double/parseDouble ?next-lat)
             :track/next-longitude (Double/parseDouble ?next-long)}))))

Not especially happy with the last bit, but haven't been able to figure out a better way that doesn't generate 'extra' entries. What I'm trying to express is that the element after timeAtPosition will be either a ncsmTrackData or ncsmRouteData tag, but if it's a ncsmTrackData it may or may not contain a nextEvent with a lat/long.