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Today's Topics:
1. Difference between Monad composition and transformation
(Song Zhang)
2. Re: shared files / environment / portability (Henk-Jan van Tuyl)
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Message: 1
Date: Sat, 25 Aug 2012 09:15:20 +0100
From: Song Zhang <[email protected]>
Subject: [Haskell-beginners] Difference between Monad composition and
transformation
To: [email protected]
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<CACGMEOnGugMmzifyFR57z-mT_CFYDB5dMi3xnHsHHsi8NHC=h...@mail.gmail.com>
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When I use a State Monad transformer to combine with a Writer Monad
StateT s (Writer w) a. is it different from composition of State Monad and
Writer Monad. It is State s (Writer w a) ?
StateT is defined as (s -> m (a, s)), so StateT s (Writer w) a can be
regarded as (s -> Writer w a) , which is (s -> ((a,w),s)
and on the other hand State s (Writer w a) is (s -> ((a,w),s). I suppose
the are similar and if so, what is the point we still get Monad
transformers? Thanks
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Message: 2
Date: Sat, 25 Aug 2012 10:28:17 +0200
From: "Henk-Jan van Tuyl" <[email protected]>
Subject: Re: [Haskell-beginners] shared files / environment /
portability
To: "Haskell Beginners" <[email protected]>, "Christopher Howard"
<[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset=iso-8859-15; format=flowed;
delsp=yes
On Sat, 25 Aug 2012 10:08:01 +0200, Henk-Jan van Tuyl <[email protected]>
wrote:
> On Sat, 25 Aug 2012 08:09:04 +0200, Christopher Howard
> <[email protected]> wrote:
>
>> I'm coding a resource tracker for a game that loads images, sounds, etc.
>> from files, and wondering how the program will know where the files are
>> located on the installation system. (With C/C++ programs I usually had
>> the build system hardcode the appropriate share/ directory into the
>> config.h file.) Assuming I package for cabal distribution, what
>> approaches to this problem are available to me?
>
>
> You can find an example in wxAsteroids[0], look at the main function.
Another example can be found in the FRP version of wxAsteroids[1], e.g.:
rock = bitmap $ getDataFile "rock.ico"
Regards,
Henk-Jan van Tuyl
[1]
https://github.com/HeinrichApfelmus/reactive-banana/blob/master/reactive-banana-wx/src/Asteroids.hs
--
http://Van.Tuyl.eu/
http://members.chello.nl/hjgtuyl/tourdemonad.html
Haskell programming
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