Making a core app with a function having context in core2core plugin?

[Magesh B]

Hi GHC Devs,

Is it possible to make a core app with a function having contexts?
For example, let us take

showable :: P.Show a => a -> String
showable = P.show

Say, I would like to app showable with (Just 'a') in the core, which
requires the following code

showable
    @ (Maybe Char)
    *($fShowMaybe @ Char $fShowChar)*
    (Just @ Char (C# 'a'))

But I couldn't find a way to construct the dictionary required by showable
function myself in the core.
Is there any ghc api using which I can get the required dictionary for a
particular type (in the above case, Dictionary for Show instance of Maybe
Char).

Regards,
Magesh B
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