oops, for the sake of completeness you also need:
textType = mkStringType "Data.Text"
- jeremy
On Oct 9, 2009, at 10:33 AM, Jeremy Shaw wrote:
Sweet!
What are the chances of seeing a, instance Data Text, some day? text
would be a great type to use with Happstack, because it is far more
memory efficient than String. But it is difficult to do that with
out a instance of Data.
For the time being, I have been hacking it with:
instance Data Text where
toConstr x = mkStringConstr textType (Text.unpack x)
gunfold _k z c = case constrRep c of
(StringConstr x) -> z (Text.pack x)
_ -> error "gunfold for Data.Text"
dataTypeOf _ = textType
But, packing and unpacking the Text is obviously not that cool..
For what it's worth, ByteString is normally exported abstract, and
just uses, deriving Data. Perhaps we can do the same for text? (I
believe there are a number of other examples of types in the
'standard' libraries which are exported abstract, but have Data
instances...)
- jeremy
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