We have slightly improved our automatic generator of regular expressions by examples (mentioned in http://news.ycombinator.com/item?id=4682545 posted by http://news.ycombinator.com/user?id=ColinWright).
We also described how the system works—very informally and very briefly---and list some of the open questions.
The webapp generates regular expressions automatically, only by means of text extraction examples. An example is a string coupled with the substring to be extracted: