JSON Sugar and other Goodness
Commas are optional at the end of fields. This is also true for the last field. The convention is to omit them.
CUE borrows a trick from Go to achieve this: the formal grammar still requires commas, but the scanner inserts commas according to a small set of simple rules.
commas.cue:
{ one: 1 two: 2 "two-and-a-half": 2.5 }
$ cue export commas.cue
{ "one": 1, "two": 2, "two-and-a-half": 2.5 }