Einar Karttunen wrote:

What is the correct way to use Data.Version.parseVersion? It seems to start with the "wrong" result and the last one is the intended one. e.g. "1.2.3" is parsed as:

[(Version {versionBranch = [1], versionTags = []},".2.3"), (Version {versionBranch = [1,2], versionTags = []},".3"), (Version {versionBranch = [1,2,3], versionTags = []},"")]

This is different from the usual read instances. Is the behaviour intended? Should I just use that as:

filter (null . snd) $ readP_to_S parseVersion "1.2.3" :: [(Version,String)]

It was intentional, but I'm prepared to be persuaded that it should be done differently. The problem is that all the parses are valid, it just depends how much of the string you want to munch. Perhaps the parser should just be greedy. You can't really compare this to other Read instances - for good reasons this isn't the Read insance for Data.Version. It's just a custom parser for versions. Cheers, Simon