ifcxt

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mkIfCxtInstances ''Typeable doesn't seem to find any instances of Typeable, which in turn means the cxtShowTypeable example doesn't work:

> :t typeRep
typeRep :: Typeable a => proxy a -> TypeRep
> typeRep [id :: Int -> Int]
Int -> Int
> cxtShowTypeable (id :: Int -> Int)
"<<unshowable>>"

Presumably this is due to Typeable's deriving-only property, which might be hard/impossible to work around. Either way, I think the example should be removed, since it gives the impression that ifcxt can look up Typeable, and caused me much head-scratching when I kept getting the else branch in my code.

Which version of ghc are you using? This was working for me on 7.10.2.

This doesn't work for me on 8.6.5.

Newer versions of GHC have changed the interface to Typeable, so unfortunately it won't work. It shouldn't be much work to add support for these newer versions, but I don't think the package has enough userbase to justify the effort for me personally.