[Haskell-beginners] type vs data, again...

[David McBride]

If you hover over "type Object = HashMap Text Value" in
Data.Aeson.Types in hackage, you will see that the HashMap link links
to http://hackage.haskell.org/packages/archive/unordered-containers/0.2.3.0/doc/html/Data-HashMap-Strict.html#t:HashMap,
which tells you what package it came from and what to import.

On Sun, Mar 17, 2013 at 11:16 AM, Emmanuel Touzery <etouzery at gmail.com> wrote:
> Thank you, that was the trick! It would be handy it there was a way through
> the online hackage packages pages to click through the dependencies. I guess
> you checked the .cabal by hand or used some slightly more arcane cabal
> commands to get that information.
>
> Thank you again and nice rest of week-end!
>
> Emmanuel
>
>
> On Sun, Mar 17, 2013 at 2:51 PM, Andres Löh <andres at well-typed.com> wrote:
>>
>> Hi again.
>>
>> >  thank you for the tip! It helps but it's not quite there yet. If you
>> > see
>> > the program in attachment, I can make it compile only by commenting the
>> > type
>> > declaration for the second function, otherwise it's the exact same error
>> > message as before.
>>
>> You're probably using the wrong HashMap. There are several packages on
>> Hackage implementing similarly-named data structures (which is
>> confusing, I know, but such is life in a decentralized and open
>> world). You should use what aeson is using (because that's the library
>> defining the Object type synonym).
>>
>> Looking at the import list of
>>
>>
>> http://hackage.haskell.org/packages/archive/aeson/0.6.0.2/doc/html/src/Data-Aeson-Types-Internal.html
>>
>> we see
>>
>> import Data.HashMap.Strict (HashMap)
>>
>> and by checking the package dependencies of aeson, we figure out that
>> this module is provided by the unordered-containers package.
>>
>> Cheers,
>>   Andres
>>
>> --
>> Andres Löh, Haskell Consultant
>> Well-Typed LLP, http://www.well-typed.com
>>
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>
>
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