[Haskell-beginners] question about list processing

[akash g]

I think these changes came with GHC 7.10.  I also completely agree that
this is difficult for beginners.  They should've had a beginner's Prelude
or something :)



On Thu, Nov 12, 2015 at 7:18 PM, Dennis Raddle <dennis.raddle at gmail.com>
wrote:

> Speaking of lists and history, I noticed that a lot of library functions
> which were formerly defined over lists (when I first looked at Haskell six
> years ago) are now defined on Traversable, which makes it a lot harder for
> beginners to read the documentation. I have been playing with Haskell for
> five years, but not much, so I'm still a beginner. I just mentally
> substitute lists when I see Traversable.
>
> I only really use lists and Maybe, as far as instances of the typeclasses
> go. That's only two types, but a lot to learn!
>
> D
>
>
>
>
> On Thu, Nov 12, 2015 at 5:42 AM, akash g <akaberto at gmail.com> wrote:
>
>>
>> http://stackoverflow.com/questions/7463500/why-do-we-have-map-fmap-and-liftm
>> have very good answers on this.
>>
>> On Thu, Nov 12, 2015 at 7:11 PM, akash g <akaberto at gmail.com> wrote:
>>
>>> map is specialized for lists while fmap is for any functors.  Its
>>> presence is historical.  Prefer fmap over map.
>>>
>>> On Thu, Nov 12, 2015 at 7:03 PM, Dennis Raddle <dennis.raddle at gmail.com>
>>> wrote:
>>>
>>>> Just after I posted that question, I started driving home, and on the
>>>> drive I thought of your answer. I think I'm starting to ask the right
>>>> questions when I'm programming in Haskell. Like redundancy and bloat is a
>>>> sure sign that a more witty expression is available, and that I should
>>>> consult the typeclasses.
>>>>
>>>> Second, I am not used to the implications of laziness, so it took me a
>>>> while to hit on your solution because I keep thinking you have to map
>>>> something over the whole list, and that if you only want to map it over the
>>>> head, you are stuck.
>>>>
>>>> You can use 'map' also, instead of 'fmap', right? Is 'map' just 'fmap'
>>>> for lists?
>>>>
>>>> D
>>>>
>>>>
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>>>>
>>>
>>
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>
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