[Haskell-cafe] PVP question

[Johan Tibell]

On Mon, Dec 15, 2014 at 8:24 PM, Dan Burton <danburton.email at gmail.com>
wrote:
>
> Or, since the PVP already encourages a cautious over-estimate of what
> constitutes a breaking change, perhaps we should go with this fallback:
> "when in doubt, call it a major change."
>

I think this makes sense. Unless you can convince yourself that the change
doesn't break backwards compatibility (i.e. doesn't break code that uses
only qualified imports and/or explicit import lists) bump the major version
number.

We should take the guesswork out of this. We should enumerate all possible
API change variations and the corresponding version number bump. Even
better, we should have a tool (like Elm has) that does so for you.


>
> -- Dan Burton
>
> On Mon, Dec 15, 2014 at 9:10 AM, Roman Cheplyaka <roma at ro-che.info> wrote:
>
>> 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 <michael at snoyman.com
>> > <mailto:michael at 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
>>
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