Demo

Macro JSONStructure(Buffer, Type, Callback)
  Define Json_#Type = CreateJSON(#PB_Any)
  If IsJSON(Json_#Type)
    InsertJSONStructure(JSONValue(Json_#Type), Buffer, Type)
    Define Result.s = ComposeJSON(Json_#Type, #PB_JSON_PrettyPrint)
    CallFunctionFast(Callback, @Result)
    FreeJSON(Json_#Type)
  EndIf
EndMacro

Structure DEMO
  a.i
  b.l
EndStructure

Define demo.DEMO

demo\a = 10
demo\b = 77

Procedure Callback(Json.s)
  Debug Json
EndProcedure

JSONStructure(@demo, DEMO, @Callback())