A method, device, and computer program product are provided for regular expression learning is provided. An initial regular expression may be received from a user. The initial regular expression is executed over a database. Positive matches and negative matches are labeled. The initial regular expression and the labeled positive and negative matches are input in a transformation process. The transformation process may iteratively execute character class restrictions, quantifier restrictions, negative lookaheads on the initial regular expression to transform the initial regular expression into the pool of candidate regular expressions. The transformation process may execute, one at a time, the character class restrictions, quantifier restrictions, the negative lookaheads. A candidate regular expression is selected from the pool of candidate regular expressions, where the selected candidate regular expression has a best F-Measure out of the pool of candidate regular expressions.