sep_by: Separated-by combinator
In kcf-jackson/combinatorParser: Build parsers with ease!

Separated-by combinator

1	sep_by(p, sep)

`p`	A parser.
`sep`	A parser.

p14 <- sep_by(one_of(as.character(0:9)), literal(","))
p14("1,")        # success:  list("1", ","))
p14("1,2,")      # success:  list("12", ","))
p14("1,2,;")     # success:  list("12", ",;"))
p14("1,2,3,;")   # success:  list("123", ",;"))
p14("1;2,;")     # success:  list("1", ";2,;"))
p14(",1,2,3,;")  #   fail :  list()