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Today's Topics:

   1. Re:  Is there an "unscan" function? (Stephen Tetley)
   2.  Can I upload file using http-enumerator, hxt? (??????? ???)
   3.  gui pkgs (Andy)


----------------------------------------------------------------------

Message: 1
Date: Fri, 13 Jan 2012 18:19:49 +0000
From: Stephen Tetley <stephen.tet...@gmail.com>
Subject: Re: [Haskell-beginners] Is there an "unscan" function?
Cc: beginners@haskell.org
Message-ID:
        <cab2tprdwb+oys03_nfb8uve0pojirfwkkvayffu_sz0ck9w...@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

Hi Jeffrey

My version actually contains an error, it should be:

unscan :: (a -> a -> b) -> [a] -> [b]
unscan f (a:b:bs) = f a b : unscan f (b:bs)
unscan _ _        = []

A slightly less concise, but optimized version avoids putting the
second element back in a list:

unscan f (a:b:bs) = f a b : go b bs
  where
    go _ [] = []
    go x (z:zs) = f x z : go z zs
unscan _ _        = []

The first mention of "speed" for traversing lists at different rates
I've seen was in the paper "There and Back Again" by Olivier Danvy and
Mayer Goldberg.

http://www.brics.dk/RS/02/12/BRICS-RS-02-12.pdf

Best wishes

Stephen



------------------------------

Message: 2
Date: Sat, 14 Jan 2012 02:44:02 +0700
From: ??????? ??? <leon.v.niki...@pravmail.ru>
Subject: [Haskell-beginners] Can I upload file using http-enumerator,
        hxt?
To: beginners@haskell.org
Message-ID: <150611326483...@web31.yandex.ru>
Content-Type: text/plain

Hello.

Can I upload file using http-enumerator, hxt?

What best way to take a html page from one server, maybe make some 
transformation of this html and upload it (transformed) to other server?

I can use hxt to download file and to do some transformation. But how can I 
upload it to other server? 



------------------------------

Message: 3
Date: Fri, 13 Jan 2012 15:34:24 -0500
From: Andy <abla...@gmail.com>
Subject: [Haskell-beginners] gui pkgs
To: beginners@haskell.org
Message-ID: <4f109550.7060...@gmail.com>
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"

Hi
  I'm trying to create a calculator in Haskell, something like the one 
in the enclosed image. To program the gui , I thought i might use a 
toolkit such as wxHaskell to create the buttons and frame etc.. I 
followed all the instructions on the wxHaskell homepage and everything 
seemed to install properly. Next I tried to use it with ghci, but to no 
avail.  It seems you have to register wxHaskell with ghci by using a 
command like <ghci -package wx> but that crashes . Every tutorial I read 
didn't work. Does anyone have a clear set of instructions,that does 
work? Also, is there a better toolkit for doing guis than wxHaskell?  I 
tried Glade, but it's so bug-ridden I couldn't get anything done. I need 
help.


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