Name of units in plugins

Matthew Pickering matthewtpickering at gmail.com
Mon Feb 18 08:11:33 UTC 2019


I described another way to do it in the second paragraph of the email.
Does that not work?

Matt

On Mon, Feb 18, 2019 at 8:10 AM Spiwack, Arnaud <arnaud.spiwack at tweag.io> wrote:
>
> Indeed, I missed the package-qualifer in findImportedModule. It does look plausible. If there is no recommended/better way to do this sort of thing, I think I'll go for it.
>
> If other plugin authors want to share their experience on what worked and didn't for them. I'd love to hear it, too. Seems like a common sort of problems in plugins.
>
> /Arnaud
>
> On Fri, Feb 15, 2019 at 9:41 AM Matthew Pickering <matthewtpickering at gmail.com> wrote:
>>
>> Did you have a look at the implementation of `findImportedModule`? I
>> think you can use it and set the final argument to `Just
>> "assert-plugin"` so that it only looks for the module in the
>> `assert-plugin` package.
>>
>> Another way people do this is to use a Template Haskell quote and then
>> use `GhcPlugins.thNameToGhcName`. Which is probably the most robust
>> way of persisting a name between the two stages.
>>
>> Cheers,
>>
>> Matt
>>
>> On Fri, Feb 15, 2019 at 8:31 AM Spiwack, Arnaud <arnaud.spiwack at tweag.io> wrote:
>> >
>> > Dear all,
>> >
>> > (first, I don't know if this is the best place for questions/discussions about the GHC API, if not, let me know where to redirect the conversation).
>> >
>> > I've been writing a plugin that substitutes call to a function by calls to another (it's a plugin reimplementation of the assert feature of GHC). And to be able to point at the names of these two functions, I need to construct a name (well, and OccName) made of three parts: unit id, module name, definition name.
>> >
>> > This question is about the unit name. Currently I simply use stringToUnitId. But the real name of my unit has a magic string in it (see https://github.com/aspiwack/assert-plugin/blob/a538d72581bae43ebf44c332e19c5ffdd28911df/src/With/Assertions.hs#L53 ). It's rather unpleasant, it seems to change every time the cabal file change (at least).
>> >
>> > The assert-explainer plugin uses another approach, only using the module name, then calling findImportedModule ( https://github.com/ocharles/assert-explainer/blob/dc6ea213d4d0576954ec883eeabeafc80c5ca18f/plugin/AssertExplainer.hs#L71-L81 ).
>> >
>> > This is much more robust to changes, but is also less precise (technically, there can be several imported modules with the same name, with package-qualified imports).
>> >
>> > So, the question is: is there a better, recommended way to recover the OccName (or Name!) of a function I defined in the same unit my plugin is defined in.
>> >
>> > Best,
>> > Arnaud
>> > _______________________________________________
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>> > ghc-devs at haskell.org
>> > http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs


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