Generics missing Data instances...

2004-02-26 Thread MR K P SCHUPKE 

There appears to be no instance for Double values in the
Generics.Basic

Also no instance for Ptr.

am I not importing the right file, or does this need to be fixed?

Regards,
Keean Schupke.

PS. This is with ghc-6.2
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Generics... no Tuples > 2 either...

2004-02-26 Thread MR K P SCHUPKE 

Any chance of Data instances for tuples of size
greater than 2... One of the nice things about generics is
you can use them by deriving Data on your datatypes - of
course this doesn't work if you all of a sudden have to 
put a load of boiler-plate in just to use tuples...

Regards,
Keean Schupke
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Re: Generics... no Tuples > 2 either...

2004-02-26 Thread Abraham Egnor 
I've been frustrated by the same lack of instances; as a stopgap, here's
one for a three-tuple.  The pattern is pretty clear and can easily be
extended to whatever size you'd like.

tupCon = mkConstr 1 "(,,)" Prefix

instance (Data a, Data b, Data c) => Data (a, b ,c) where
gfoldl k z (a, b, c) = ((z (,,) `k` a) `k` b) `k` c
toConstr _ = tupCon
fromConstr _ = (undefined, undefined, undefined)
dataTypeOf _ = mkDataType [tupCon]

MR K P SCHUPKE <[EMAIL PROTECTED]> writes:
>
>Any chance of Data instances for tuples of size
>greater than 2... One of the nice things about generics is
>you can use them by deriving Data on your datatypes - of
>course this doesn't work if you all of a sudden have to 
>put a load of boiler-plate in just to use tuples...
>
>   Regards,
>   Keean Schupke
>___
>Glasgow-haskell-users mailing list
>[EMAIL PROTECTED]
>http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
>



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