<span style="font-family: arial,sans-serif;">I'm running ghc-6.7.20070802 and getting a new error message that didn't show up with ghc-6.6. Code:</span><br style="font-family: arial,sans-serif;"><br style="font-family: arial,sans-serif;">
<span style="font-family: courier new,monospace;"> -- | Pairing for unary type constructors.</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> newtype Pair1 f g a = Pair1 {unPair1 :: (f a, g a)}
</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> deriving (Eq, Ord, Show)</span><br style="font-family: arial,sans-serif;"><br style="font-family: arial,sans-serif;">
<span style="font-family: arial,sans-serif;">Error message:</span><br style="font-family: arial,sans-serif;"><br style="font-family: arial,sans-serif;"><span style="font-family: courier new,monospace;"> src/Data/Tupler.hs:26:0:
</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> No instances for (Show (g a), Show (f a))</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">
arising from the 'deriving' clause of a data type declaration</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> at src/Data/Tupler.hs:(26,0)-(27,25)
</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> Possible fix:</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;">
add an instance declaration for (Show (g a), Show (f a))</span><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"> When deriving the instance for (Show (Pair1 f g a))
</span><br style="font-family: arial,sans-serif;"><br style="font-family: arial,sans-serif;"><span style="font-family: arial,sans-serif;">Has there been a change to "deriving"? Is there a workaround?<br><br>Thanks, - Conal
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