Illegal type synonym family application in instance (Was: Breakage with 6.10)

Niklas Broberg niklas.broberg at
Fri Oct 10 20:40:40 EDT 2008

>  A breakdown of the remaing causes for DependencyFailed,
>       [...]
>       4 hsx-0.4.4

src/hsx$ runhaskell Setup build
[snip warnings]

    Illegal type synonym family application in instance: XML m
    In the instance declaration for `EmbedAsChild m (XML m)´

Could someone help me point out the problem here? The relevant code is:

instance XMLGen m => EmbedAsChild m (XML m) where
 asChild = return . return . xmlToChild

class XMLGen m => EmbedAsChild m c where
 asChild :: c -> GenChildList m

class Monad m => XMLGen m where
 type XML m

This works fine with 6.8.3, so what's new in 6.10, and what would I do
to solve it?

Btw, I also have problems with the haskell-src-exts that imports
Data.Generics.Instances (to generate Data and Typeable instances).
Where would these have moved to in the new base? And how would I make
the code work with both 6.8.3 and 6.10?



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