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Today's Topics:
1. Re: latest Haskell Platform build fails (Adam Mesha)
2. Re: Functors and Applicatives; I'm just not getting it ...
(Frank)
3. Re: Functors and Applicatives; I'm just not getting it ...
(Erik Price)
4. Re: Functors and Applicatives; I'm just not getting it ...
(Francesco Ariis)
5. Is working with Haskell easier on Linux than on a Mac?
(Jeffrey Brown)
----------------------------------------------------------------------
Message: 1
Date: Sun, 19 Oct 2014 16:45:17 +0300
From: Adam Mesha <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] latest Haskell Platform build fails
Message-ID:
<capfoczc5psylq1p1mecao+rjv7ijynlrfox-f1jwolpywjj...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
2014-10-18 22:09 GMT+03:00 emacstheviking <[email protected]>:
> Lurker speaks: I too came to the same conclusion as Michael a long time
> back; I absolutely love Haskell but sooner or later it seemed to me that
> the "dependancy hell" would kick in just when you least needed / expected
> it to. It is the single biggest put off for me now to consider using it.
>
Does this dependency hell problem still exist when you use cabal sandboxes?
--
Adam Mesha <[email protected]>
Life is either a daring adventure, or nothing. - Helen Keller
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Message: 2
Date: Sun, 19 Oct 2014 09:51:33 -0400
From: Frank <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] Functors and Applicatives; I'm just
not getting it ...
Message-ID:
<CA+a3wkKDBkzTHSnw51iszpS_tZVRiLoP=+g4xejyswx4jv5...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Thanks but I think this misses the point a bit. A some point in time, I
will need an explanation about applicatives and teg supposedly best
documentation (or at least the documentation I see advocated in numerous
places) seems really bad at providing that explanation, a point I find
worrisome. I know myself well enough to say becoming comfortable with
functors will not make understanding applicatives any easier if the
applicatives explanation is not clear and, right now, the explanation is
not clear.
On Sunday, October 19, 2014, Karl Voelker <[email protected]> wrote:
> I suggest that you ignore applicatives for now and just focus on plain-old
> functors. They are the simplest part, and once you are confident in dealing
> with them, adding on applicatives will be much easier.
>
> And, although it can be difficult when you are really lost, if you can ask
> some more specific questions, this list will provide plenty of answers.
>
> -Karl
>
> > On Oct 18, 2014, at 3:37 PM, Frank <[email protected]
> <javascript:;>> wrote:
> >
> > 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++?
> >
> > --
> > P.S.: I prefer to be reached on BitMessage at
> BM-2D8txNiU7b84d2tgqvJQdgBog6A69oDAx6
> > _______________________________________________
> > Beginners mailing list
> > [email protected] <javascript:;>
> > http://www.haskell.org/mailman/listinfo/beginners
> _______________________________________________
> Beginners mailing list
> [email protected] <javascript:;>
> http://www.haskell.org/mailman/listinfo/beginners
>
--
P.S.: I prefer to be reached on BitMessage at
BM-2D8txNiU7b84d2tgqvJQdgBog6A69oDAx6
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Message: 3
Date: Sun, 19 Oct 2014 10:39:29 -0400
From: Erik Price <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] Functors and Applicatives; I'm just
not getting it ...
Message-ID:
<CAD+X7c-+kgx-ktSA6CFSyRS-jHB5ansKNu=9vcwhgqmxy6r...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
As the name implies, the concept of an applicative functor builds on the
concept of a functor, so it will help to start with a thorough
understanding of functors.
A functor allows you to lift a function of Foo -> Bar into some context of
Foo, so that when the expression is finally evaluated you will end up with
a value of Bar in that context. An applicative functor allows you to lift a
function of an arbitrary number of parameters, such as Foo -> Bar ->
Baz, into that number of values (of those types) already in contexts. So
the example function could be applied to a context of Foo and a context of
Bar, and would ultimately evaluate to a context of Baz.
e
On Sunday, October 19, 2014, Frank <[email protected]> wrote:
> Thanks but I think this misses the point a bit. A some point in time, I
> will need an explanation about applicatives and teg supposedly best
> documentation (or at least the documentation I see advocated in numerous
> places) seems really bad at providing that explanation, a point I find
> worrisome. I know myself well enough to say becoming comfortable with
> functors will not make understanding applicatives any easier if the
> applicatives explanation is not clear and, right now, the explanation is
> not clear.
>
> On Sunday, October 19, 2014, Karl Voelker <[email protected]
> <javascript:_e(%7B%7D,'cvml','[email protected]');>> wrote:
>
>> I suggest that you ignore applicatives for now and just focus on
>> plain-old functors. They are the simplest part, and once you are confident
>> in dealing with them, adding on applicatives will be much easier.
>>
>> And, although it can be difficult when you are really lost, if you can
>> ask some more specific questions, this list will provide plenty of answers.
>>
>> -Karl
>>
>> > On Oct 18, 2014, at 3:37 PM, Frank <[email protected]> wrote:
>> >
>> > 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++?
>> >
>> > --
>> > P.S.: I prefer to be reached on BitMessage at
>> BM-2D8txNiU7b84d2tgqvJQdgBog6A69oDAx6
>> > _______________________________________________
>> > Beginners mailing list
>> > [email protected]
>> > http://www.haskell.org/mailman/listinfo/beginners
>> _______________________________________________
>> Beginners mailing list
>> [email protected]
>> http://www.haskell.org/mailman/listinfo/beginners
>>
>
>
> --
> P.S.: I prefer to be reached on BitMessage at
> BM-2D8txNiU7b84d2tgqvJQdgBog6A69oDAx6
>
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Message: 4
Date: Sun, 19 Oct 2014 16:48:58 +0200
From: Francesco Ariis <[email protected]>
To: [email protected]
Subject: Re: [Haskell-beginners] Functors and Applicatives; I'm just
not getting it ...
Message-ID: <[email protected]>
Content-Type: text/plain; charset=us-ascii
On Sun, Oct 19, 2014 at 09:51:33AM -0400, Frank wrote:
> Thanks but I think this misses the point a bit. A some point in time, I
> will need an explanation about applicatives and teg supposedly best
> documentation (or at least the documentation I see advocated in numerous
> places) seems really bad at providing that explanation, a point I find
> worrisome. I know myself well enough to say becoming comfortable with
> functors will not make understanding applicatives any easier if the
> applicatives explanation is not clear and, right now, the explanation is
> not clear.
Applicatives are Functors, so a solid understanding of the latter is required
to grasp the former.
- Did you go through all the examples from Learn You a Haskell [1]?
- Could you write the `instance Functor Tree` if asked?
- There are instances like `Functor ((->) r)` and `Functor ((,) a)`;
how do they behave? Could you rewrite them *not* to follow Functor laws?
Once you feel comfortable with the more mind bending cases of Functor,
Applicative will be way easier to understand.
[1]
http://learnyouahaskell.com/making-our-own-types-and-typeclasses#the-functor-typeclass
------------------------------
Message: 5
Date: Sun, 19 Oct 2014 13:13:50 -0700
From: Jeffrey Brown <[email protected]>
To: [email protected]
Subject: [Haskell-beginners] Is working with Haskell easier on Linux
than on a Mac?
Message-ID:
<caec4ma2xn7u_zxyc+j6sngn+vbaulw0q2bcrs+r+qou3kt9...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
I have read that Haskell is easier to work with on Linux than on Windows.
Is Haskell on Linux also easier than Haskell on OS X?
I'm trying to do realtime OSC output from Haskell, because concurrency in
Python is hard. Brandon Allbery on the haskell-cafe list, told me "chrt"
and "sched_setscheduler" would be helpful. At the shell prompt I found that
my system (OS X 10.9) does not recognize "chrt". I found a library on
Hackage, "posix-realtime", that claims Mac compatibility and has a
"sched_setscheduler" function, but my attempts to install it fail:
sh-3.2# cabal install posix-realtime
Resolving dependencies...
Downloading unix-2.3.2.0...
Configuring unix-2.3.2.0...
Building unix-2.3.2.0...
Failed to install unix-2.3.2.0
Last 10 lines of the build log ( /var/root/.cabal/logs/unix-2.3.2.0.log ):
Building unix-2.3.2.0...
Preprocessing library unix-2.3.2.0...
dist/build/System/Posix/Signals.hs:124:10:
fatal error: 'Signals.h' file not found
#include "Signals.h"
^
1 error generated.
Even if I found a solution to this particular problem, I'm worried I'll
keep running into similar ones, because I'm sure I'll keep trying new
packages. Would this kind of work be substantially easier if I were using,
say, Linux Mint?
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