[Haskell-beginners] Functors and Applicatives; I'm just not getting it ...

Adam Mesha adam.raizen at gmail.com
Sun Oct 19 09:16:59 UTC 2014


The way I have come to understand them (based on playing around with them
and various tutorials) is that a functor is a mappable, something that can
be mapped.  Or, since fmap is equivalent to liftM, you could call them
liftables.  So if I have a function of type a -> b and a functor (let's say
Maybe), then it makes sense that I can automatically create a function
Maybe a -> Maybe b (thus lifting the function into the Maybe functor, or
mapping a to b through (over/using) the Maybe functor).

2014-10-19 1:37 GMT+03:00 Frank <frankdmartinez at gmail.com>:

> I've had a go at LYAH and CIS 194 and the Typeclassopedia and I just don't
> get get functors and applicatives. I'm simply not understanding them, what
> the various symbols/keywords mean, what they represent, how to think of
> them, etc. Nothing. Is there any kind of documented model I should be
> considering? Is there a "functors and applicatives for Dummies" I should
> read? Should I just give it up, not bother with Haskell and just stick to
> scheme/ruby/C++?
>
> --
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-- 
Adam Mesha <adam.raizen at gmail.com>
Life is either a daring adventure, or nothing. - Helen Keller
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