The approach I tried taking (but couldn't get quite right, ran out of time and abandoned) was to create two new combinators, which I called "manyR" and "many1R"

The approach I tried taking (but couldn't get quite right, ran out of time and abandoned) was to create two new combinators, which I called "manyR" and "many1R". These behaved like Parsec's built-in "many" and "many1" combinators except that on failure they would print the error (using unsafePerformIO) and attempt recovery. I really should try to get those working, because I think they would be useful additions to Parsec.