[Haskell-cafe] advanced class constraints in Haskell 98?

Miguel Mitrofanov miguelimo38 at yandex.ru
Thu Jan 8 19:03:14 EST 2009


On 9 Jan 2009, at 02:47, Ross Paterson wrote:

> On Thu, Jan 08, 2009 at 10:27:59PM +0100, Henning Thielemann wrote:
>> A nice. I jumped into 4.3 and found
>>
>> scontext -> simpleclass
>>         | (simpleclass_1, ..., simpleclass_n)
>>
>> simpleclass -> qtycls tyvar
>>
>> So it must be 'atype' instead of 'tyvar'? Haskell 98 is really  
>> mighty.
>
> Oh.  Don't I look silly?  You were absolutely right, it's not  
> Haskell 98.

Me too. I've looked at the type declaration syntax instead of instance  
declaration one.

>
>
> Actually Hugs does reject it without flags.  Maybe you have a -98  
> stored
> somewhere?
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