added some docs

src/compiler/serialize.c

@@ -1,3 +1,20 @@
+
+/*  -- WHAT IS THIS FILE? --
+ *
+ *   This file implements the routines that serialize the AST
+ * into JSON format. The JSON manipulation is handled by the
+ * third party library xJSON (written by me, still). 
+ *   The serialization functionality is exposed through the 
+ * `serialize` function, that takes as an `AST` as argument
+ * and outputs a string of valid JSON. Therefore the xJSON
+ * dependency isn't exposed to the caller and can be regarded
+ * as an implementation detail.
+ *   The way the serialization occurres is by converting the
+ * AST's representation native to the compiler to one native
+ * to xJSON, an then calling xj_encode on the converted AST.
+ *
+ */
+
 #include <assert.h>
 #include <xjson.h>
 #include "serialize.h"