Refactoring based on feedback from Mike and Tom.

Rename `parse` -> `parser`, `format` -> `formatter`.  Parser now calls
`map` setters instead of returning an array.

polymaps.js

@@ -2,7 +2,7 @@ if (!org) var org = {};
 if (!org.polymaps) org.polymaps = {};
 (function(po){
 
-  po.version = "2.3.0"; // semver.org
+  po.version = "2.4.0"; // semver.org
 
   var zero = {x: 0, y: 0};
 po.ns = {
@@ -1763,11 +1763,19 @@ po.hash = function() {
       lat = 90 - 1e-8, // allowable latitude range
       map;
 
-  var parse = function(s) {
-    return s.split("/").map(Number);
+  var parser = function(s) {
+    var args = s.split("/").map(Number);
+    if (args.length < 3 || args.some(isNaN))
+      move(); // replace bogus hash
+    else {
+      var size = map.size();
+      map.zoomBy(args[0] - map.zoom(),
+          {x: size.x / 2, y: size.y / 2},
+          {lat: Math.min(lat, Math.max(-lat, args[1])), lon: args[2]});
+    }
   };
 
-  var format = function(map) {
+  var formatter = function(map) {
     var center = map.center(),
         zoom = map.zoom(),
         precision = Math.max(0, Math.ceil(Math.log(zoom) / Math.LN2));
@@ -1777,21 +1785,13 @@ po.hash = function() {
   };
 
   function move() {
-    var s1 = format(map);
+    var s1 = formatter(map);
     if (s0 !== s1) location.replace(s0 = s1); // don't recenter the map!
   }
 
   function hashchange() {
     if (location.hash === s0) return; // ignore spurious hashchange events
-    var args = parse((s0 = location.hash).substring(1));
-    if (!args || args.length == undefined || args.length < 3 || args.some(isNaN))
-      move(); // replace bogus hash
-    else {
-      var size = map.size();
-      map.zoomBy(args[0] - map.zoom(),
-          {x: size.x / 2, y: size.y / 2},
-          {lat: Math.min(lat, Math.max(-lat, args[1])), lon: args[2]});
-    }
+    parser((s0 = location.hash).substring(1));
   }
 
   hash.map = function(x) {
@@ -1808,17 +1808,17 @@ po.hash = function() {
     return hash;
   };
 
-  hash.parse = function(x) {
-    if (!arguments.length) return parse;
-    parse = x;
+  hash.parser = function(x) {
+    if (!arguments.length) return parser;
+    parser = x;
     return hash;
-  }
+  };
 
-  hash.format = function(x) {
-    if (!arguments.length) return format;
-    format = x;
+  hash.formatter = function(x) {
+    if (!arguments.length) return formatter;
+    formatter = x;
     return hash;
-  }
+  };
 
   return hash;
 };