[REQ] [Elm] generate list of enum values

Created by: andys8

There enum generation results in a tagged union like this:

type PaymentsPerYear
    = Monthly
    | Quarterly
    | Halfyearly
    | Yearly

It would be super nice if there would also be an enumeration in form of a List or Set. This way it's made sure that the list of values is complete.

paymentsPerYear = [ Monthly, Quarterly, Halfyearly, Yearly ]

This is basically solving a feature the language Elm is currently missing and maybe a bit more than what to expect from the generator but it would be super nice :)