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Today's Topics:
1. Re: Haskell for server? (C K Kashyap)
2. Help needed in understanding MonadWriter syntax. (Vinay Emani)
3. Re: Help needed in understanding MonadWriter syntax.
(divyanshu ranjan)
4. Re: Haskell for server? (Miro Karpis)
5. Re: Haskell for server? (Erik de Castro Lopo)
6. Re: Help needed in understanding MonadWriter syntax.
(Kim-Ee Yeoh)
----------------------------------------------------------------------
Message: 1
Date: Mon, 16 Sep 2013 09:49:41 +0530
From: C K Kashyap <[email protected]>
To: [email protected], The Haskell-Beginners Mailing List -
Discussion of primarily beginner-level topics related to Haskell
<[email protected]>
Subject: Re: [Haskell-beginners] Haskell for server?
Message-ID:
<CAGdT1goNfZs=ketpogdpx-eurrkfne3x+mjthrgmrtz1a+e...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
I'd suggest you take a look at yesod as well before deciding on the web
framework.
Regards,
Kashyap
On Sun, Sep 15, 2013 at 12:58 PM, Miro Karpis <[email protected]>wrote:
> Please can you help me with following?
> I would like to try Haskell in our company. We need to make a simulation
> data server that would do read/write requests into a DB (didn't decide on a
> DB yet). Read/write will be done by several clients - so far I think that
> we might have around 1000 clients. Size of the transferred data will be
> quite small (maximum 10 MB). Every client can have around 10 requests per
> second. All the network will be in-house (local). It needs to be stable and
> fast, since our clients will be a modules that do physics calculations. It
> should also support parallelism, concurrency and in the future maybe cloud
> computing.
>
> Snap framework looks very promising, but am not 100% sure.
>
> Please do you have any suggestions to what framework and DB would be
> appropriate to this set-up?
>
> Cheers,
> m.
>
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://www.haskell.org/mailman/listinfo/beginners
>
>
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Message: 2
Date: Sun, 15 Sep 2013 22:00:34 -0700
From: Vinay Emani <[email protected]>
To: [email protected]
Subject: [Haskell-beginners] Help needed in understanding MonadWriter
syntax.
Message-ID:
<CAODqeuAXgqML7S7v1ZMxb=RmgUwdz1i709i=rxgwhu7qzf7...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Hi,
I'm trying to understand the MonadWriter class definition syntax. Now, I'm
using GHC 7.6 and the class is defined as
class (Monoid w, Monad m) => MonadWriter w m | m -> w where
....
I've never seen '|' in the middle of a class definition, could some one
explain this? It's used in the guard syntax as well as to separate data
constructors in a type definition.
Regards
Vinay
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Message: 3
Date: Mon, 16 Sep 2013 10:38:52 +0530
From: divyanshu ranjan <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] Help needed in understanding
MonadWriter syntax.
Message-ID:
<cal9hw24pentryjjoamvk3cmhfsxdewwojxhb5pegwsh_pn4...@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
This is functional dependency. For this case It means for given monad
m, there is unique possible value of Monoid w.
http://en.wikipedia.org/wiki/Type_class#Functional_dependencies
http://research.microsoft.com/pubs/67435/jfp06.pdf
Thanks
Divyanshu Ranjan
On Mon, Sep 16, 2013 at 10:30 AM, Vinay Emani <[email protected]> wrote:
> Hi,
>
> I'm trying to understand the MonadWriter class definition syntax. Now, I'm
> using GHC 7.6 and the class is defined as
>
> class (Monoid w, Monad m) => MonadWriter w m | m -> w where
> ....
>
> I've never seen '|' in the middle of a class definition, could some one
> explain this? It's used in the guard syntax as well as to separate data
> constructors in a type definition.
>
> Regards
> Vinay
>
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://www.haskell.org/mailman/listinfo/beginners
>
------------------------------
Message: 4
Date: Mon, 16 Sep 2013 07:11:33 +0200
From: Miro Karpis <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] Haskell for server?
Message-ID:
<cajnnbxhaupxxgmfybtioxltyamh9gtgodw3sozkyh8f6ow2...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Would like to correct/add on thing. I'm not looking for a server that will
host a we page. I'm looking for a server that will handle TCP
requests/connections.
cheers,
m.
On Mon, Sep 16, 2013 at 6:19 AM, C K Kashyap <[email protected]> wrote:
> I'd suggest you take a look at yesod as well before deciding on the web
> framework.
>
> Regards,
> Kashyap
>
>
> On Sun, Sep 15, 2013 at 12:58 PM, Miro Karpis
> <[email protected]>wrote:
>
>> Please can you help me with following?
>> I would like to try Haskell in our company. We need to make a simulation
>> data server that would do read/write requests into a DB (didn't decide on a
>> DB yet). Read/write will be done by several clients - so far I think that
>> we might have around 1000 clients. Size of the transferred data will be
>> quite small (maximum 10 MB). Every client can have around 10 requests per
>> second. All the network will be in-house (local). It needs to be stable and
>> fast, since our clients will be a modules that do physics calculations. It
>> should also support parallelism, concurrency and in the future maybe cloud
>> computing.
>>
>> Snap framework looks very promising, but am not 100% sure.
>>
>> Please do you have any suggestions to what framework and DB would be
>> appropriate to this set-up?
>>
>> Cheers,
>> m.
>>
>> _______________________________________________
>> Beginners mailing list
>> [email protected]
>> http://www.haskell.org/mailman/listinfo/beginners
>>
>>
>
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Message: 5
Date: Mon, 16 Sep 2013 15:21:35 +1000
From: Erik de Castro Lopo <[email protected]>
To: [email protected]
Subject: Re: [Haskell-beginners] Haskell for server?
Message-ID: <[email protected]>
Content-Type: text/plain; charset=US-ASCII
Miro Karpis wrote:
> Would like to correct/add on thing. I'm not looking for a server that will
> host a we page. I'm looking for a server that will handle TCP
> requests/connections.
The network-conduit package has a network server framework that works
much like Warp (the Yesod web server). That would be a good place to
start.
Erik
--
----------------------------------------------------------------------
Erik de Castro Lopo
http://www.mega-nerd.com/
------------------------------
Message: 6
Date: Mon, 16 Sep 2013 15:05:14 +0700
From: Kim-Ee Yeoh <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] Help needed in understanding
MonadWriter syntax.
Message-ID:
<CAPY+ZdStPsdcXUSrt+osstrzhk-itWm4t8tDRW7x+u=jhot...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
On Mon, Sep 16, 2013 at 12:00 PM, Vinay Emani <[email protected]> wrote:
> I've never seen '|' in the middle of a class definition, could some one
> explain this? It's used in the guard syntax as well as to separate data
> constructors in a type definition.
You're quite right. The vertical bar is used in /defining/
(1) a /typeclass/ that has functional dependencies
(2) a /function/ using pattern guards
(3) a /datatype/ that is a sum of two or more datatypes.
These are all different, as you've guessed. The reason the syntax
conflation works is that all these constructs are different.
The canonical intro to fundeps is the container/element example. See
Section 3 on collection types in
http://web.cecs.pdx.edu/~mpj/pubs/fundeps.html
-- Kim-Ee
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