Is there a way to find all typeclasses of type in Template Haskell

Asked Jun 06 '15 at 15:49

Active Jun 06 '15 at 17:09

Viewed 60 times

The question is in the title. Given a type, is there a way to find all the typeclasses it instantiates. I'm try to get the list of fields generated by makeField (lens).Example

 data Point = Point { _x :: Double, _y :: Double } deriving (Show).

I would like given Point to get [HasX, HasY, Show]. Alternatively, is there a way to get all the Name in scope ?

edited Jun 06 '15 at 17:09

asked Jun 06 '15 at 15:49

mb14

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Why would you need that? Just curious. You certainly can't find typeclasses defined in modules you don't import; as far as I can tell TH doesn't have any way to enumerate "whatever is visible from here". – n. m. could be an AI Jun 06 '15 at 16:41
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I'm trying to automatically instanciate typeclass for sum types. – mb14 Jun 06 '15 at 17:09
How would you instantiate e.g. a Monad for a sum type? – n. m. could be an AI Jun 06 '15 at 17:58
I'm only instantiating typeclasses following a certain pattern, not every typeclasses. – mb14 Jun 06 '15 at 18:14

Is there a way to find all typeclasses of type in Template Haskell

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