[Haskell-cafe] ANNOUNCE: Generic Haskell 1.80 (Emerald)

Brandon S. Allbery KF8NH allbery at ece.cmu.edu
Sat Apr 12 13:51:31 EDT 2008

On Apr 12, 2008, at 13:33 , Thomas van Noort wrote:
>> On 12/04/2008, Thomas van Noort <thomas at cs.ru.nl> wrote:
>>> That's a good question. Unfortunately, only Haskell98 types are
>>> currently
>>>  supported by the Generic Haskell compiler.
>> I thought constrained types were Haskell 98, but now I'm in doubt...
> language. Generic Haskell is fully reflexive with respect to the types
> that are definable in Haskell 98, except for constraints in data-type
> definitions. So a data type of the form
> data Eq a => Set a = NilSet | ConsSet a (Set a)
> is not dealt with correctly. However, constrained data types are a  
> corner
> case in Haskell and can easily be simulated using other means.

I was under the impression "corner case" here means that H98 lets you  
write it but doesn't handle it very sanely (a GHC-specific extension  
being needed to achieve that).

brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allbery at kf8nh.com
system administrator [openafs,heimdal,too many hats] allbery at ece.cmu.edu
electrical and computer engineering, carnegie mellon university    KF8NH

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