Passing categories and attributes

Hi,
I'm having trouble with product creation. I can't figure out how to pass the categories and the attributes, it keeps showing "rest_invalid_param" error code with message "categories[0] not of type object".
I first thought it should be an object array, but it didn't work. I also tried with a map, but there is no way to make it work.
Could you please give me an example of how should I do it?