An optional parser may or may not consume input off the stream. Given a parser p, p optional = p or: DerivingParser emptyString. (Name: Parsing-Derivatives-fbs.17
Author: fbs
Time: 17 April 2013, 8:54:37.782 pm
UUID: 2f4da7f3-2323-4b1d-8e17-3ddc659d5762
Ancestors: Parsing-Derivatives-fbs.16)