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Today's Topics:
1. Re: Parser composition (Angelos Bimpoudis)
2. Error building internal Scion server, how to solve it?
(Guofeng Zhang)
3. Re: Error building internal Scion server, how to solve it?
(Amy de Buitl?ir)
4. Re: Error building internal Scion server, how to solve it?
(Amy de Buitl?ir)
5. defining 'init' in terms of 'foldr' (Paul Higham)
6. Re: defining 'init' in terms of 'foldr' (Daniel Fischer)
7. Exception back trace (Russ Abbott)
----------------------------------------------------------------------
Message: 1
Date: Sat, 4 Dec 2010 15:15:27 +0200
From: "Angelos Bimpoudis" <[email protected]>
Subject: Re: [Haskell-beginners] Parser composition
To: <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"
Thank you all for the answers. There is a hell of a trip ahead!
> -----Original Message-----
> From: Henk-Jan van Tuyl [mailto:[email protected]]
> Sent: Friday, December 03, 2010 2:37 PM
> To: [email protected]; Angelos Bimpoudis
> Subject: Re: [Haskell-beginners] Parser composition
>
> On Thu, 02 Dec 2010 23:50:16 +0100, Angelos Bimpoudis
> <[email protected]>
> wrote:
>
> >
> > I am trying to understand what is the f in p>>=f in each one of above
> > sequencing applications?
>
> Maybe "A tour of the Haskell Monad functions" can help:
> http://members.chello.nl/hjgtuyl/tourdemonad.html
>
> Regards,
> Henk-Jan van Tuyl
>
>
> --
> http://Van.Tuyl.eu/
> http://members.chello.nl/hjgtuyl/tourdemonad.html
> --
------------------------------
Message: 2
Date: Sun, 5 Dec 2010 00:51:33 +0800
From: Guofeng Zhang <[email protected]>
Subject: [Haskell-beginners] Error building internal Scion server, how
to solve it?
To: [email protected]
Message-ID:
<[email protected]>
Content-Type: text/plain; charset="iso-8859-1"
Hi,
Installed Haskell Platform 2010.2.0.0 on Windows, then install EclipseFP 2
Latest Release 2.0.2 on Helios 3.6.1. JDK 1.6.0_21. But the internal Scion
server cannot be built, so I cannot compile my Haskell code.
How to solve it?
The following error message is displayed on the Eclipse console when I
launch Eclipse:
Resolving dependencies...
selecting
cabal.exe: cannot configure scion-0.1.0.6. It requires AttoJson >=0.5.2,
binary ==0.5.*, derive -any, ghc-paths ==0.1.*, ghc-syb -any, ghc-syb-utils
-any, hslogger ==1.0.*, list-tries -any, multiset >=0.1 && <0.3 and uniplate
-any
There is no available version of AttoJson that satisfies >=0.5.2
There is no available version of binary that satisfies ==0.5.*
There is no available version of derive that satisfies -any
There is no available version of ghc-paths that satisfies ==0.1.*
There is no available version of ghc-syb that satisfies -any
There is no available version of ghc-syb-utils that satisfies -any
There is no available version of hslogger that satisfies ==1.0.*
There is no available version of list-tries that satisfies -any
There is no available version of multiset that satisfies >=0.1 && <0.3
There is no available version of uniplate that satisfies -any
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Message: 3
Date: Sat, 4 Dec 2010 17:33:32 +0000
From: Amy de Buitl?ir <[email protected]>
Subject: Re: [Haskell-beginners] Error building internal Scion server,
how to solve it?
To: Guofeng Zhang <[email protected]>
Cc: [email protected]
Message-ID:
<[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
> Latest Release 2.0.2 on Helios 3.6.1. JDK 1.6.0_21. But the internal Scion
> server cannot be built, so I cannot compile my Haskell code.
I had a similar problem. To work around it, I manually installed the
packages, making sure that they were installed globally. For example:
cabal install --global AttoJson
Then restart Eclipse, and it should see the new packages.
------------------------------
Message: 4
Date: Sat, 4 Dec 2010 17:39:37 +0000
From: Amy de Buitl?ir <[email protected]>
Subject: Re: [Haskell-beginners] Error building internal Scion server,
how to solve it?
To: Guofeng Zhang <[email protected]>
Cc: [email protected]
Message-ID:
<[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
>> Latest Release 2.0.2 on Helios 3.6.1. JDK 1.6.0_21. But the internal Scion
>> server cannot be built, so I cannot compile my Haskell code.
Actually, I think you have a different problem: you have the wrong
version of Scion. You can't use the one in Cabal. Get the right
version from:
http://code.google.com/p/scion-lib/
Go into the directory where you put it, and type: cabal install --global
Once you get that fixed, you may or may not need the workaround I
described above.
------------------------------
Message: 5
Date: Sat, 4 Dec 2010 14:20:51 -0800
From: Paul Higham <[email protected]>
Subject: [Haskell-beginners] defining 'init' in terms of 'foldr'
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
Not sure if this thread is still active but I also struggled with this
same exercise. I offer the following solution as a thing to shoot at:
myInit :: [a] -> [a]
myInit ys = foldr snoc [] $ (\(x:xs) -> xs) $ foldr snoc [] ys
where snoc = (\x xs -> xs ++ [x])
Note that snoc is defined at the top of the same page as the exercise
in Simon's book.
::paul
------------------------------
Message: 6
Date: Sat, 4 Dec 2010 23:48:03 +0100
From: Daniel Fischer <[email protected]>
Subject: Re: [Haskell-beginners] defining 'init' in terms of 'foldr'
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset="iso-8859-1"
On Saturday 04 December 2010 23:20:51, Paul Higham wrote:
> Not sure if this thread is still active but I also struggled with this
> same exercise. I offer the following solution as a thing to shoot at:
>
> myInit :: [a] -> [a]
> myInit ys = foldr snoc [] $ (\(x:xs) -> xs) $ foldr snoc [] ys
> where snoc = (\x xs -> xs ++ [x])
init === reverse . tail . reverse
only holds for finite lists, for infinite lists xs, reverse xs = _|_, but
init xs = xs.
Also, it's inefficient, but that's not the point of the exercise.
>
> Note that snoc is defined at the top of the same page as the exercise
> in Simon's book.
>
> ::paul
Cheers,
Daniel
------------------------------
Message: 7
Date: Sat, 4 Dec 2010 16:49:42 -0800
From: Russ Abbott <[email protected]>
Subject: [Haskell-beginners] Exception back trace
To: beginners <[email protected]>
Message-ID:
<[email protected]>
Content-Type: text/plain; charset="iso-8859-1"
Hi,
I am in the midst of debugging and got an exception:
*** Exception: Prelude.minimum: empty list
That's all it said. There was no information about where the exception
occurred. Is it possible to ask for more information, preferably including a
stack trace?
Thanks.
*
-- Russ *
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