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Today's Topics:
1. Re: can this be made shorter? (Tilmann)
2. Re: can this be made shorter? (Emmanuel Touzery)
3. Re: can this be made shorter? (Henk-Jan van Tuyl)
4. Re: Categories in Haskell (Ertugrul S?ylemez)
5. Re: Categories in Haskell (Robert Goss)
6. Re: Categories in Haskell (Peter Hall)
7. Re: Cabal Dependency Hell (Peter Hall)
----------------------------------------------------------------------
Message: 1
Date: Wed, 29 May 2013 22:00:58 +0200
From: Tilmann <[email protected]>
Subject: Re: [Haskell-beginners] can this be made shorter?
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
you might want to use 'all' as well:
Prelude> (all $ flip elem "./") "...."
True
Am 29.05.2013 21:50, schrieb Emmanuel Touzery:
> null . dropWhile (`elem` "./")
------------------------------
Message: 2
Date: Wed, 29 May 2013 22:14:44 +0200
From: Emmanuel Touzery <[email protected]>
Subject: Re: [Haskell-beginners] can this be made shorter?
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Message-ID:
<cac42rekzljszxol68qivsst6vydxmm8ty0rwxfch3-bwgmz...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
ah, i wrote "and" but i meant "all" in my emails ;-)
but yes i thought about all in combination with the null, to go over "."
and "/".
yes this is clearer, just too bad about the flip.
On Wed, May 29, 2013 at 10:00 PM, Tilmann <[email protected]> wrote:
> you might want to use 'all' as well:
>
> Prelude> (all $ flip elem "./") "...."
> True
>
>
> Am 29.05.2013 21:50, schrieb Emmanuel Touzery:
>
> null . dropWhile (`elem` "./")
>>
>
>
> ______________________________**_________________
> Beginners mailing list
> [email protected]
> http://www.haskell.org/**mailman/listinfo/beginners<http://www.haskell.org/mailman/listinfo/beginners>
>
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Message: 3
Date: Wed, 29 May 2013 22:14:57 +0200
From: "Henk-Jan van Tuyl" <[email protected]>
Subject: Re: [Haskell-beginners] can this be made shorter?
To: "The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell" <[email protected]>,
Tilmann <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset=iso-8859-15; format=flowed;
delsp=yes
On Wed, 29 May 2013 22:00:58 +0200, Tilmann <[email protected]> wrote:
> you might want to use 'all' as well:
>
> Prelude> (all $ flip elem "./") "...."
> True
or:
all (`elem` "./") "...."
Regards,
Henk-Jan van Tuyl
--
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just 5 minutes you can join the world's biggest networked computer and get
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--
------------------------------
Message: 4
Date: Wed, 29 May 2013 23:04:18 +0200
From: Ertugrul S?ylemez <[email protected]>
Subject: Re: [Haskell-beginners] Categories in Haskell
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset="us-ascii"
Robert Goss <[email protected]> wrote:
> The main issue is that the objects of the category (represented by
> the id morphism) are in bijection to some set of haskell types.
>
> [...]
>
> Now this all makes sense Haskell's categories are for reasoning about
> programs while I want to use it more for pure maths. Has anyone else
> had a similar problem with categories in haskell? Or am I missing a
> way of implementing such structures within the standard Category
> framework for haskell.
Perhaps what you need is not a programming language like Haskell, but a
proof assistant like Agda, where you can express arbitrary categories.
A limited form of this is possible in Haskell as well, but the lack of
dependent types would force you through a lot of boilerplate and heavy
value/type/kind lifting.
Greets,
Ertugrul
--
Not to be or to be and (not to be or to be and (not to be or to be and
(not to be or to be and ... that is the list monad.
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Message: 5
Date: Wed, 29 May 2013 23:11:29 +0100
From: Robert Goss <[email protected]>
Subject: Re: [Haskell-beginners] Categories in Haskell
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Message-ID:
<canrvqsa-psgvzkyzgyb6im1ayp2gspcb1o8zfoxem8jtrc4...@mail.gmail.com>
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On 29 May 2013 22:04, Ertugrul S?ylemez <[email protected]> wrote:
>
>
> Perhaps what you need is not a programming language like Haskell, but a
> proof assistant like Agda, where you can express arbitrary categories.
> A limited form of this is possible in Haskell as well, but the lack of
> dependent types would force you through a lot of boilerplate and heavy
> value/type/kind lifting.
>
>
I had had a look at Agda a while ago I will have to have another look. How
possible is it to do computations in Agda? For example is it possible to
compute the equalizer of 2 arrows (obv is a category in which equalizers
exit)?
A part of this was a learning experience it seemed natural to express
certain bits of computer algebra in terms of categories and I wanted to see
how well these ideas could be expressed in haskell.
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Message: 6
Date: Thu, 30 May 2013 00:15:31 +0100
From: Peter Hall <[email protected]>
Subject: Re: [Haskell-beginners] Categories in Haskell
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Message-ID:
<caa6hak7hvd+2mcbmcbaz1jhmg-fewnntx_xpigsim+nzqxv...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
I haven't tried Idris yet myself, and I'm not sure how stable it is, but I
think it can do a lot that Agda can do but more suitable for actual
calculations. I would be interested to hear any experiences you have (or
have had) with it.
Peter
On 29 May 2013 23:11, Robert Goss <[email protected]> wrote:
>
>
>
> On 29 May 2013 22:04, Ertugrul S?ylemez <[email protected]> wrote:
>
>>
>>
>> Perhaps what you need is not a programming language like Haskell, but a
>> proof assistant like Agda, where you can express arbitrary categories.
>> A limited form of this is possible in Haskell as well, but the lack of
>> dependent types would force you through a lot of boilerplate and heavy
>> value/type/kind lifting.
>>
>>
> I had had a look at Agda a while ago I will have to have another look. How
> possible is it to do computations in Agda? For example is it possible to
> compute the equalizer of 2 arrows (obv is a category in which equalizers
> exit)?
>
> A part of this was a learning experience it seemed natural to express
> certain bits of computer algebra in terms of categories and I wanted to see
> how well these ideas could be expressed in haskell.
>
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://www.haskell.org/mailman/listinfo/beginners
>
>
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Message: 7
Date: Thu, 30 May 2013 00:32:58 +0100
From: Peter Hall <[email protected]>
Subject: Re: [Haskell-beginners] Cabal Dependency Hell
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Message-ID:
<caa6hak6uzfca+mgafqyery5f0fbws8v3ya1ikkhfoixorgw...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
> The GHC devs know a better solution is needed; unfortunately, the best
they've come up with is a proposal to build everything against
> everything else in every possible combination....
Surely that isn't necessary; it could be done lazily. That is, compile
every combination that is actually demanded by their respective cabal
files. No?
Peter
On 28 May 2013 15:58, Brandon Allbery <[email protected]> wrote:
> On Tue, May 28, 2013 at 3:37 AM, harry <[email protected]> wrote:
>
>> Brandon Allbery <allbery.b <at> gmail.com> writes:
>> > Why isn't this avoided by installing packages without inlining?
>> Packages ...
>> >
>> > Because the performance is somewhere between horrible and abysmal.
>>
>> Thank you, does this mean that dynamic linking wouldn't work either?
>
>
> Dynamic linking is an even bigger ball of snakes, yes. :/ A better
> solution would be nice, but I'm not aware of any magic that can be applied
> to it. (The GHC devs know a better solution is needed; unfortunately, the
> best they've come up with is a proposal to build everything against
> everything else in every possible combination....) Not that there are any
> better ideas sitting around. Maybe whole program compilation, which would
> require all libraries to be available in source form (and would make
> dynamic linking meaningless since every compiled library would be a
> one-off).
>
> --
> brandon s allbery kf8nh sine nomine
> associates
> [email protected]
> [email protected]
> unix, openafs, kerberos, infrastructure, xmonad
> http://sinenomine.net
>
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