[Haskell-cafe] Re: derive & Drift - some help please

[Alexander Dunlap]

Well you can do

> deriving instance Typeable LocalType

etc. if you enable the DeriveDataTypeable and StandaloneDeriving
extensions. You will get other error messages for missing instances;
just keep adding

> deriving instance Typeable Day

etc. Eventually, you will need to implement an instance by hand for
Pico, because Pico's data constructors are not exported from
Data.Fixed. I'm not very familiar with Data and Typeable so I can't
help you there, but you can probably look at some existing instances
for help.

Hope that's useful for you.

Alex

On Sun, Mar 8, 2009 at 12:40 PM, Gü?nther Schmidt <gue.schmidt at web.de> wrote:
> Hi Alexander,
>
>
> well I have this:
>
> newtype AdmissionDate = AdmDt LocalTime
>        deriving (Data,Typeable ..)
>
> at least that's where I wonna get.
>
> I don't know how to create the proper instance declarations though for
> LocalTime.
>
> AdmissionDate is an element of a larger data structure, this data structure
> for instance also has a
>
> newtype DischargeDate = DchrgDt LocalTime
>        deriving (Data,Typeable ...)
>
> With my haskell work so far I was blessedly free of the need for deriving.
> Until now ...
>
> Günther
>
>
> Alexander Dunlap schrieb:
>>
>> What problems are you encountering?
>>
>> Alex
>>
>> On Sun, Mar 8, 2009 at 11:58 AM, G?uenther Schmidt <redcom at fedoms.com>
>> wrote:
>>>
>>> Hi Sterling,
>>>
>>> sry, but I can't get it to work.
>>>
>>> Günther
>>>
>>> Sterling Clover schrieb:
>>>>
>>>> You shouldn't need any extra tools for this. A combination of the
>>>> StandaloneDeriving and DeriveDataTypeable extensions in GHC should
>>>> suffice.
>>>>
>>>> Cheers,
>>>> S.
>>>>
>>>> On Sun, Mar 8, 2009 at 10:30 AM, Gü?nther Schmidt <gue.schmidt at web.de
>>>> <mailto:gue.schmidt at web.de>> wrote:
>>>>
>>>>   Hi,
>>>>
>>>>   I need to derive Data, Typeable for Data.Time.LocalTime. I had hoped
>>>>   to use either derive or DrIFT to generate the instance declarations
>>>>   for it.
>>>>
>>>>   I tried to understand the respective user manuals but it's still all
>>>>   Greek to me.
>>>>
>>>>   Someone please help!
>>>>
>>>>   Günther
>>>>
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