Fixed glyphs file serializer to match Glyphs nuances

FiraCode.glyphs

@@ -1,7 +1,7 @@
 {
 .appVersion = "1131";
 DisplayStrings = (
-"flask\012Flask\012fiber\012fj\012/f_l.liga lflask\012Tla\012/f_t.liga"
+"flask\012Flask\012fiber\012fji\012Tla"
 );
 classes = (
 {
@@ -97,7 +97,6 @@ value = 1;
 {
 name = fsType;
 value = (
-
 );
 },
 {
@@ -114923,7 +114922,6 @@ unitsPerEm = 1950;
 userData = {
 GSDimensionPlugin.Dimensions = {
 "B67F0F2D-EC95-4CB8-966E-23AE86958A69" = {
-
 };
 "BF448B58-7A35-489E-A1C9-12628F60690C" = {
 HH = 141;
@@ -114947,4 +114945,4 @@ oV = 98;
 };
 versionMajor = 1;
 versionMinor = 207;
-}
+}

clojure/glyphs.clj

@@ -109,7 +109,7 @@
 
 (def escape-re #"[\n\"\\]")
 
-(defn serialize [form]
+(defn- serialize-impl [form]
   (cond
     (string? form)     (if (re-matches #"[a-zA-Z0-9._/]+" form)
                          form 
@@ -118,14 +118,21 @@
     (number? form)     (str form)
     (instance? clojure.lang.MapEntry form)
                        (str
-                         (serialize (key form))
+                         (serialize-impl (key form))
                          " = "
                          (if (= ".appVersion" (key form)) ;; https://github.com/googlefonts/glyphsLib/issues/209
                            (str \" (val form) \")
-                           (serialize (val form)))
+                           (serialize-impl (val form)))
                          ";")
-    (sequential? form) (str "(\n" (str/join ",\n" (map serialize form)) "\n)")
-    (map? form)        (str "{\n" (str/join "\n" (map serialize form)) "\n}")))
+    (sequential? form) (if (empty? form)
+                         "(\n)"
+                         (str "(\n" (str/join ",\n" (map serialize-impl form)) "\n)"))
+    (map? form)        (if (empty? form)
+                         "{\n}"
+                         (str "{\n" (str/join "\n" (map serialize-impl form)) "\n}"))))
+
+(defn serialize [font]
+  (str (serialize-impl font) "\n"))
 
 ; (-> (slurp "FiraCode.glyphs") parse serialize (->> (spit "FiraCode_saved.glyphs")))