Does this look right? Translating from javascript to clojurescript

d3_geo.cljs

(defn- build-map [svg topo-obj]
  (let [subunits (.-subunits (.-objects topo-obj))
        geo (.-geo js/d3)
        feature (.-feature js/topojson)
        mercator (.-mercator geo)]
    (.. svg
        (append "path")
        (datum (feature topo-obj subunits))
        (attr "d"
              (.. geo
                  (path)
                  (projection (mercator)))))))

d3_geo_example.js

// From http://bost.ocks.org/mike/map/
d3.json("uk.json", function(error, uk) {
  if (error) return console.error(error);

  svg.append("path")
      .datum(topojson.feature(uk, uk.objects.subunits))
      .attr("d", d3.geo.path().projection(d3.geo.mercator()));
});

generated_code.js

// I'm not sure this looks correct -t he calls to e.g. feature turning into feature.call with the first arg being null is unexpected.
map_brazil.core.build_map = (function build_map(svg,topo_obj){
    var subunits = topo_obj.objects.subunits;
    var geo = d3.geo;
    var feature = topojson.feature;
    var mercator = geo.mercator;
    return svg.append("path").datum(feature.call(null,topo_obj,subunits)).attr("d",geo.path().projection(mercator.call(null)));
});