Operations on list

Hello all

I want to work with lists, but I can't find the necessary objects.

1) How do I calculate the intervals between the elements of a list of integers? For example: (12 15 19 23) => (3 4 4)

2) How do I create a second list from this list of intervals, starting from a specific starting point? For example: 60 (3 4 4) => 60 63 67 71

Thanks a lot !

AB