Re: [Haskell-cafe] PVP question

Almost any API change can break existing code. For example, adding a new function can break code. I thought the guiding principle for PVP was how likely it is that a piece of client code will break, not if that's theoretically possible. On 15/12/14 11:44, Johan Tibell wrote:

I think the question is: can this change cause existing code to stop compiling (perhaps assuming people aren't using -Werror)? I don't think it can but perhaps generalizing the type could make type inference fail somewhere due to an ambiguous type.

We really need a PVP guide that just lists lots of examples, each with a note of what kind of change it is (i.e. major, minor, or patch).

On Mon, Dec 15, 2014 at 10:00 AM, Michael Snoyman mailto:michael@snoyman.com> wrote:

I'm a little bit uncertain of the PVP guidelines in a certain case[1], so I'd like to get some guidance/clarity. Suppose I have a library which provides the function:

myFunction :: IO () myFunction = forever $ putStrLn "Still here" >> threadDelay 10^6

Later, I realize (or someone points out to me) that I've over-specified the type signature, and really myFunction should be:

myFunction :: IO a

In this case, does the PVP specify that we should have a minor or a major version bump? I'm not certain if this counts as a breaking change or not.

[1] https://github.com/fpco/streaming-commons/pull/13