[Haskell-cafe] GHC API: type class instance check

[MigMit]

I'm no expert in GHC plugins, but isn't it true that class instances can be added in other modules? So that this information is simply not available when compiling one?

> On 11 Nov 2016, at 08:57, J. Stutterheim <j.stutterheim at me.com> wrote:
> 
> Hi all,
> 
> I'm writing a core-to-core GHC plugin and have two questions:
> 
> - Given some t :: Type, how can I check whether there exists an instance of some type class C for t?
> - How can I check whether some type class C exists, and if so, how can I get a value c (presumably :: Class) of this class?
> 
> Thanks!
> 
> - Jurriën_______________________________________________
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