Name of units in plugins

Matthew Pickering matthewtpickering at
Fri Feb 15 08:40:55 UTC 2019

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.



On Fri, Feb 15, 2019 at 8:31 AM Spiwack, Arnaud <arnaud.spiwack at> 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 ). 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 ( ).
> 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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