[Haskell-beginners] Application of lookup function

[Jeon-Young Kang]

Thanks Alex.

I successfully implemented what I want by using 'elem'.

On Thu, Dec 3, 2015 at 11:50 PM, Alex Belanger <i.caught.air at gmail.com>
wrote:

> The (`elem` members) function will tell you if the person is a member of
> members. You can then turn that boolean into your custom State type.
> On Dec 3, 2015 11:46 PM, "Jeon-Young Kang" <jykang22 at gmail.com> wrote:
>
>> Hi all.
>>
>> I'd like to apply lookup function (Data.Map) for what I am working on.
>>
>> Here is my code.
>>
>> data Person = Person {personId :: Int, name = String}
>> data People = [Person]
>>
>> data State = InMembership | NoMemebership
>>
>> person1 = Person {1 = personId, "James" = name}
>> person2 = Person {2 = personId, "Tom" = name}
>>
>> members = People [person1, person2]
>>
>> class Belonging a where
>>       belonging :: a -> [a] -> Bool -> State
>>
>> here is the problem...
>> I don't know how to get to know whether a person is belong to members.
>> I'd like to find it through a person's name.
>>
>> Can you suggest any examples??
>>
>> Sincerely,
>> Jeon
>>
>>
>>
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>>
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-- 
Department of Geography
State University of New York at Buffalo

jykang22 at gmail.com

Jeon-Young Kang
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