[Haskell-beginners] LYAHFGG, chapter 11 question

[Karolis Velicka]

I actually found the Typeclassopedia's explanation of functors,
applicatives and monads fairly intuitive, in spite of its intimidating
appearance. You can find it here
http://www.haskell.org/haskellwiki/Typeclassopedia

Best wishes,
Karl (Karolis) Velicka


On 29 August 2014 16:00, Gareth <gareth.tpc at gmail.com> wrote:
> Actually, I remember that that chapter being difficult too, so much so that
> I don't think I finished it. It might be worth coming back to that chapter
> later, after you have more practical experience.
>
> In the mean time though, if I could tell you only one fact about how to use
> Applicative, it would be this.
>
> Say you have some pure function:
>
> f :: Int -> Int -> Int -> Int
>
> And some values that may or may not be in the context of some Applicative
> functor (let's say Maybe)
>
> x :: Maybe Int
> y :: Int
> z :: Maybe Int
>
> Then you can call f like this:
>
> (f <$> x <*> pure y <*> z  ) :: Maybe Int
>
> So if you were in the middle of some do notation you could
>
> do
>    myF <- f <$> x <*> pure y <*> z
>    ...
>
> rather than the more painful
>
> do
>    x' <- x
>    z' <- z
>    let myF = f x' y z'
>    ...
>
>
>
>
>
>
>
> On Wed, Aug 27, 2014 at 10:22 AM, Peter Hall <peterjoel at gmail.com> wrote:
>>
>> > I learned a new word today, “Sisyphean.”
>>
>> Me too! :)
>>
>> Peter
>>
>>
>> On 27 August 2014 04:21, Jeff C. Britton <jcb at iteris.com> wrote:
>>>
>>> I had originally encountered problems at this point myself.  I lost
>>> motivation because I had just had this feeling that programming with
>>> applicatives was just not going to be fun, and it was beginning to seem like
>>> Haskell programming might involve a lot of this.  I put the book down for
>>> about 1 year.  Somewhere I came across an article on Monads that changed my
>>> mind.  I started over and am now almost done with Chapter 13.  This time
>>> around things are looking a lot cooler.  I think chapters 11,12, and 13 may
>>> lack the motivational information to keep one going.  I can say that the
>>> author Miran Lipovaca really does a great job of explaining this material.
>>> I don’t think you are going to find a better source.  Absolutely every step
>>> of the way is laid out in painstaking detail.  Plus there are constant
>>> reminders of material that was just covered that is relevant to the
>>> immediate situation.  All I can say is go slow and make sure you understand
>>> every detail before proceeding.  Keep at it regularly so as not to forget
>>> important terms.  Go back and reread if necessary.  Have the confidence that
>>> it will be worthwhile.  The Monad chapters are little bit more interesting,
>>> but you will need to understand the applicatives first.  I learned a new
>>> word today, “Sisyphean.”
>>>
>>>
>>>
>>> From: Beginners [mailto:beginners-bounces at haskell.org] On Behalf Of Frank
>>> Sent: Tuesday, August 26, 2014 7:33 PM
>>> To: The Haskell-Beginners Mailing List - Discussion of primarily
>>> beginner-level topics related to Haskell
>>> Subject: [Haskell-beginners] LYAHFGG, chapter 11 question
>>>
>>>
>>>
>>> About "Learn You a Haskell ...", is it My imagination or is chapter 11
>>> absurdly long and/or thick? I can (and have) read a 100+ page U.S. Supreme
>>> Court ruling, readily understand it, and be able to explain it in plain
>>> English, with next to zero trouble. I spend every work day reading, parsing,
>>> interpreting, and using, the ISO C++ standard. I taught My undergraduate
>>> Physics IV class while simultaneously taking it. Yet, chapter 11 feels as if
>>> it goes on and on to the point I easily forget what I read just a few lines
>>> before, rendering comprehension of the same an almost Sisyphean task. Is it
>>> just Me? Am I just tired? Is there an alternative resource for understanding
>>> the concepts that particular chapter presents?
>>>
>>>
>>>
>>> Sincerely,
>>>
>>> Frank D. Martinez
>>>
>>>
>>>
>>> --
>>> P.S.: I prefer to be reached on BitMessage at
>>> BM-2D8txNiU7b84d2tgqvJQdgBog6A69oDAx6
>>>
>>>
>>> _______________________________________________
>>> Beginners mailing list
>>> Beginners at haskell.org
>>> http://www.haskell.org/mailman/listinfo/beginners
>>>
>>
>>
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