Refactor retrieving DataType's name

modules/lang/src/main/kotlin/io/smnp/ext/lang/function/TypeOfFunction.kt

@@ -9,7 +9,7 @@ import io.smnp.type.model.Value
 class TypeOfFunction : Function("typeOf") {
    override fun define(new: FunctionDefinitionTool) {
       new function simple(allTypes()) body { _, (obj) ->
-         Value.string(obj.type.toString()) // TODO
+         Value.string(obj.typeName)
       }
    }
 }