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Today's Topics:
1. Re: GUI library for beginners? (aditya siram)
2. Re: GUI library for beginners? (Henk-Jan van Tuyl)
3. Cheap lookup tables (Paul Sargent)
4. Re: Cheap lookup tables (Daniel Fischer)
5. Re: Cheap lookup tables (Stephen Tetley)
6. Re: GUI library for beginners? (John Smith)
7. Re: Equivalence of Inheritance (Russ Abbott)
----------------------------------------------------------------------
Message: 1
Date: Tue, 14 Dec 2010 08:53:46 -0600
From: aditya siram <[email protected]>
Subject: Re: [Haskell-beginners] GUI library for beginners?
To: Brent Yorgey <[email protected]>
Cc: [email protected]
Message-ID:
<[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
>From an ease-of-installation and getting-demos-to-work standpoint,
I've had the best time with qtHaskell [1].
-deech
[1] http://qthaskell.berlios.de/
On Tue, Dec 14, 2010 at 8:38 AM, Brent Yorgey <[email protected]> wrote:
> But OpenGL is not really a GUI library, is it? ?I think gtk2hs is
> usually recommended. I've never used it personally but have heard good
> things from those who have. ?Hopefully the web page will be back up
> soon.
>
> -Brent
>
> On Tue, Dec 14, 2010 at 09:55:45AM +0000, Tom Hobbs wrote:
>> Hi Venanzio,
>>
>> I found the following sites very helpful when trying to understand
>> OpenGL + Haskell.
>>
>> -
>> http://blog.mikael.johanssons.org/archive/2006/09/opengl-programming-in-haskell-a-tutorial-part-1/
>> - http://myawesomeblag.blogspot.com/2007/03/opengl-tetris-in-haskell.html
>>
>> My site contains the commands I used to get everything install on
>> Ubuntu, it also has a link to my code on it, but you'll find that the
>> code is very similar to Mikael's above.
>>
>> http://whatimean.wordpress.com/2010/10/19/simple-cell-automata-in-haskell/
>>
>> Good luck.
>>
>> Tom
>>
>> On Tue, Dec 14, 2010 at 9:16 AM, Venanzio Capretta <[email protected]>
>> wrote:
>> > Hi,
>> > ?I've been trying to find out what is the best GUI library to use for a
>> > Haskell beginner.
>> > At first I adopted gtk2hs and it was going well. But the web page for it
>> > has
>> > disappeared during the Haskell site migration. So now I don't have access
>> > to
>> > the documentation and the examples any more.
>> > Next I tried with wxHaskell, but unfortunately it doesn't install on Ubuntu
>> > (I checked on the mailing list: other people had the same problem and I
>> > don't understand the solution).
>> > Is there a library for GUI in Haskell that is simple to use and well
>> > supported, something that is user friendly for a beginner Haskell
>> > programmer?
>> > Best wishes,
>> > ?Venanzio
>> >
>> > _______________________________________________
>> > Beginners mailing list
>> > [email protected]
>> > http://www.haskell.org/mailman/listinfo/beginners
>> >
>>
>> _______________________________________________
>> Beginners mailing list
>> [email protected]
>> http://www.haskell.org/mailman/listinfo/beginners
>
> _______________________________________________
> Beginners mailing list
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> http://www.haskell.org/mailman/listinfo/beginners
>
------------------------------
Message: 2
Date: Tue, 14 Dec 2010 16:26:56 +0100
From: "Henk-Jan van Tuyl" <[email protected]>
Subject: Re: [Haskell-beginners] GUI library for beginners?
To: [email protected], "Venanzio Capretta" <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset=iso-8859-15; format=flowed;
delsp=yes
On Tue, 14 Dec 2010 10:16:40 +0100, Venanzio Capretta <[email protected]>
wrote:
> Next I tried with wxHaskell, but unfortunately it doesn't install on
> Ubuntu (I checked on the mailing list: other people had the same problem
> and I don't understand the solution).
To get wxHaskell working on Ubuntu (and probably on most other platforms),
you need to install the g++ compiler, see:
ftp://ftp.gnu.org/pub/gnu/gcc/gcc-4.5.1/
I guess you need the file gcc-g++-4.5.1.tar.gz
Regards,
Henk-Jan van Tuyl
--
http://Van.Tuyl.eu/
http://members.chello.nl/hjgtuyl/tourdemonad.html
--
------------------------------
Message: 3
Date: Tue, 14 Dec 2010 17:13:27 +0000
From: Paul Sargent <[email protected]>
Subject: [Haskell-beginners] Cheap lookup tables
To: beginners <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset=us-ascii
I've just done some profiling on my application, and I've found that about 50%
of my time and allocations is taken by two functions. All these are a functions
which return constants from tables.
At the moment they look something like this (I'm using the dimensional package
to handle SI Units, hence the *~ one):
buehlmannGradient :: (Fractional a) => Gas -> Int -> Dimensionless a
buehlmannGradient Nitrogen 1 = 1.7928 *~ one
buehlmannGradient Nitrogen 2 = 1.5352 *~ one
[...]
buehlmannGradient Nitrogen 15 = 1.0414 *~ one
buehlmannGradient Nitrogen 16 = 1.0359 *~ one
buehlmannGradient Helium 1 = 2.0964 *~ one
buehlmannGradient Helium 2 = 1.7400 *~ one
[...]
buehlmannGradient Helium 15 = 1.0850 *~ one
buehlmannGradient Helium 16 = 1.0791 *~ one
This one causes 36% of my time.
The other is similar:
buehlmannZeroPoint :: (Fractional a) => Gas -> Int -> Int -> Pressure a
buehlmannZeroPoint Nitrogen 1 mode = ([29.6, 29.6, 29.6] *~~ msw) !!
mode - buehlmannGradient Nitrogen 1 * (10 *~ msw)
[...]
Again, 16 Cases times two gases. This one uses 14.5%.
They tend to be called in pairs, and the first function is called about 100,000
times. The second about 50,000 times (which then causes 50,000 of the first
function).
What's my best strategy for optimising these functions? Is it the pattern match
that's hurting me? Can I write them in a better way, or do I need to look at
how I'm using them?
Obviously calling them less often would help, but I'm not sure what I'd do to
my code to achieve this. These constants are used in lots of fairly diverse
areas of my code, and they're encapsulated into functions to stop magic numbers
flying around.
Thanks
Paul
------------------------------
Message: 4
Date: Tue, 14 Dec 2010 18:28:53 +0100
From: Daniel Fischer <[email protected]>
Subject: Re: [Haskell-beginners] Cheap lookup tables
To: Paul Sargent <[email protected]>
Cc: beginners <[email protected]>
Message-ID:
<[email protected]>
Content-Type: text/plain; charset="iso-8859-1"
On Tue, Dec 14, 2010 at 6:13 PM, Paul Sargent <[email protected]> wrote:
> I've just done some profiling on my application, and I've found that about
> 50% of my time and allocations is taken by two functions. All these are a
> functions which return constants from tables.
>
<snip>
>
> They tend to be called in pairs, and the first function is called about
> 100,000 times. The second about 50,000 times (which then causes 50,000 of
> the first function).
>
> What's my best strategy for optimising these functions?
Maybe looking it up in an array helps. You'd need an Ix instance for Gas,
which is easy (I'm not sure whether Ix can be derived).
> Is it the pattern match that's hurting me?
Hard to say, but with pattern matching, it may take a lot of sequential
comparisons to find the value, which *may* cause it to use a lot of time.
> Can I write them in a better way, or do I need to look at how I'm using
> them?
>
> Obviously calling them less often would help, but I'm not sure what I'd do
> to my code to achieve this. These constants are used in lots of fairly
> diverse areas of my code, and they're encapsulated into functions to stop
> magic numbers flying around.
>
> Thanks
>
> Paul
>
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Message: 5
Date: Tue, 14 Dec 2010 17:39:08 +0000
From: Stephen Tetley <[email protected]>
Subject: Re: [Haskell-beginners] Cheap lookup tables
Cc: beginners <[email protected]>
Message-ID:
<[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
Would specializing the functions to Double then using realToFrac only
when necessary improve things? (It might make things worse of
course...)
buehlmannGradient :: Gas -> Int -> Double
------------------------------
Message: 6
Date: Tue, 14 Dec 2010 19:56:25 +0200
From: John Smith <[email protected]>
Subject: Re: [Haskell-beginners] GUI library for beginners?
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 14/12/2010 16:53, aditya siram wrote:
> From an ease-of-installation and getting-demos-to-work standpoint,
> I've had the best time with qtHaskell [1].
>
> -deech
>
> [1] http://qthaskell.berlios.de/
I've had by far the worst time with qtHaskell, but that may be a platform issue
(I'm on Windows)
I've found building WxHaskell to be a little easier than Gtk+
------------------------------
Message: 7
Date: Tue, 14 Dec 2010 10:11:08 -0800
From: Russ Abbott <[email protected]>
Subject: Re: [Haskell-beginners] Equivalence of Inheritance
To: [email protected]
Message-ID:
<[email protected]>
Content-Type: text/plain; charset="iso-8859-1"
I'm also confused about how to do the equivalence of inheritance in Haskell.
Here is a complete example below. It doesn't compile. The error message
is
Class `Person' used as a type
If I write "(Person p) =>" instead, I get other diagnostics.
I would very much appreciate seeing how this should be done in Haskell.
---------- Example (multiple files) ------------
--- Group.hs ---
module Group where
import Person
data Group = Group { members :: [Person] }
instance Show Group where
show group = unlines $ map show $ members group
--- Person.hs ---
module Person
(
Condition(Bad, OK, Good)
, Person
)
where
class Person where
age :: Person -> Int
name :: Person -> String
getGenderSpecificCondition :: Person -> Condition
instance Show Person where
show p = name p ++ "(" ++ age p ++ ", " ++ getGenderSpecificCondition p
++ ")"
data Condition = Bad | OK | Good
--- Man.hs ---
module Man
( age
, name
, Man (Man)
)
where
import Person
data Man = Man { name :: String
, age :: Int
, prostateCondition :: Condition
}
instance Person Man where
getGenderSpecificCondition :: Person -> Condition
getGenderSpecificCondition m = prostateCondition m
--- Woman.hs---
module Woman
( age
, name
, Woman (Woman)
)
where
import Person
data Woman = Woman { name :: String
, age :: Int
, ovaryCondition :: Condition
}
instance Person Woman where
getGenderSpecificCondition :: Person -> Condition
getGenderSpecificCondition w = ovaryCondition w
---------- End example (multiple files) ------------
Thanks
*-- Russ *
On Tue, Dec 14, 2010 at 12:11 AM, <[email protected]> wrote:
> Date: Mon, 13 Dec 2010 22:09:25 -0600
> From: Antoine Latter <[email protected]>
> Subject: Re: [Haskell-beginners] Equivalent of inheritance in Haskell
> To: C K Kashyap <[email protected]>
> Cc: [email protected]
> Message-ID:
> <[email protected]>
> Content-Type: text/plain; charset=UTF-8
>
> On Mon, Dec 13, 2010 at 9:10 PM, C K Kashyap <[email protected]> wrote:
> >>
> >> But there is not a way to easily say (in Haskell) "type A is
> >> everything that type B is plus these other things here ...". Haskell
> >> is not an OO language.
> >
> > This captures what I had in mind. Using compound types seems ok but
> > I'd still need to do some mechanical stuff if I had to provide a
> > function that works on the compound type which is actually defined for
> > a component type.
> >
> > If I understand you right .. you'd build a 'Man' type and 'Woman' type
> > by using a 'Person' type. Lets say, there is a function called getName
> > that is Person -> String
> > I'd have to mechanically define a function getName :: Man -> String -
> > that extracts the person inside and calls getName on it - did I
> > understand it right?
> > Or would you typically write extract functions that'll return the
> > components and then the user could call the method on the component?
> > As in .... getPerson :: Man -> Person ... then call getName on that.
> >
> > How do you deal with situations like that?
> >
>
> Well, in this case I might just have a person type with a 'gender'
> field :-) Then I get the polymorphism and code-reuse for free!
>
> But what you're talking about is something that OO-style programming
> is particularly aligned towards, and functional programming generally
> is not.
>
> One thing people do is use type-classes - this would be a bit like
> having 'Car' and 'Truck' implement the same interface. The simple
> building blocks would be duplicated, but the complex application-level
> functionality could be written against the typeclass.
>
> Another approach is with functional lenses - these are libraries that
> aim to make updating complex compound types easier. Off the top of my
> head I know of fclabels[1], but I know there are others. If you're
> interested in this approach you might be able to email the -cafe
> mailing list to ask for more.
>
> Is there a particular problem you're trying to solve? we might be able
> to take the conversation in a less speculative direction.
>
> Antoine
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