I am indebted to Joel de Guzman and Hartmut Kaiser for their expert advice during the early states of xpressive's development. I am thankful for John Maddock's excellent work on his proposal to add regular expressions to the standard library. I'd also like to thank Andrei Alexandrescu for his input regarding the behavior of nested regex objects, and Dave Abrahams for his suggestions regarding the regex domain-specific embedded language. Noel Belcourt helped porting xpressive to the Metrowerks CodeWarrior compiler.