You might be able to write some Template Haskell to derive the Show instance.
It's a bit tricky, because there are some types which can't have Show
derived, such as:
data Foo where
Broken :: a -> Foo
What should
show (Broken id)
do?
-- ryan
On Mon, Apr 13, 2009 at 9:28 PM, Norman Ram
Unfortunately, this isn't supported at present.
--Ben
On 14 Apr 2009, at 05:28, Norman Ramsey wrote:
I've got a fairly large GADT for which I wished to use
deriving (Show)
but I got a mysterious error message:
Exp.hs:13:11:
Can't make a derived instance of `Show (Exp a)'
(`Exp' has
I've got a fairly large GADT for which I wished to use
deriving (Show)
but I got a mysterious error message:
Exp.hs:13:11:
Can't make a derived instance of `Show (Exp a)'
(`Exp' has non-Haskell-98 constructor(s))
In the data type declaration for `Exp'
This is from GHC. Does any
oe
Brent Yorgey wrote:
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Haskell Weekly News
http://sequence.complete.org/hwn/20090413
Issue 113 - April 13, 2009
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Welcome to issue 113 of HWN, a newsletter covering developments in the
> I am hoping some of you may have suggestions about other papers that
> would be good tutorials in the use of GADTs.
>
> Norman
>
Norman,
This is very much in a state of flux but it may be worth taking a look at
http://code.haskell.org/asn1/ASNTYPE.lhs. There's also
http://www.haskell.org/haske
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Haskell Weekly News
http://sequence.complete.org/hwn/20090413
Issue 113 - April 13, 2009
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Welcome to issue 113 of HWN, a newsletter covering
