Fair point, and that's due to my failure in not providing an optional side-effect function arg to `parse-log-skip`. And this brings up a related point, namely that the author of the lib is still responsible for crafting the API. For example, if the author of `parseLog` had not included `recover FixEntry`, would it be possible for the caller to implement it via a condition system? Would that even be a good idea? Using the pseudo-python, the only approach I can think of would be:

    def parseLogInteractively(file):
      do:
        return parseLog(file)
      handle ParseError, e:
        line = askToFixEntry(e.text)
        retry

Perhaps this is one of those cases where a simplified example helps convey the concept, but is too simple to show where other approaches would fall short.

>mass duplication of code

I'm not clear on what you mean. Multiple functions with different behaviour seems not to altogether different from one function with implicit switches that change its behaviour.