Re: [Haskell-cafe] Re: Math questions
* sure I did enjoy the discussion here Yitzchak Gale. I have already submitted several questions ,and you guys were very helpful. However , I am not sure how I will use Haskell other than my Haskell course that has just finished. * On 28 May 2010 14:52, Ivan Lazar Miljenovic wrote: > Yitzchak Gale writes: > > > My "for" function was indeed "flip map". Perhaps it's not > > in any library, but it's often seen on the #haskell IRC > > channel. :) > > Hmmm, I had never heard of this but going back through my logs I do > indeed find nornagon, jethr0 and jmcarthur all either stating this > definition or advocating it. Alternate definitions that I found > include: > > * pam (ski) > > * -<< (vixey) > > -- > Ivan Lazar Miljenovic > ivan.miljeno...@gmail.com > IvanMiljenovic.wordpress.com > -- Mujtaba Ali Alboori ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Math questions
*Pete Chown and Dan Doel. Thank you for your solution. I actually It was not homework . It was just a a past exam question trying to answer . * **but your solution is very long , so I don't think he wants answer this long in the exams. I think this answer agree100 f g = map f xs == map g xs where xs = [1..100] from Richard O'Keefe is do the job. **Anyway , your solution help understand more about Haskell not only this question . Many thanks to you guys. On 27 May 2010 02:04, Dan Doel wrote: > On Wednesday 26 May 2010 5:38:57 pm Pete Chown wrote: > > test :: (Eq a) => (Int -> a) -> (Int -> a) -> Bool > > test f1 f2 = unsafePerformIO $ do > > goodSoFar <- newIORef True > > forLoop 1 100 $ \i -> > >when (f1 i /= f2 i) $ writeIORef goodSoFar False > > readIORef goodSoFar > > The problem with this algorithm is that it needlessly tests f1 against f2 > for > all i, even when a non-matching value has has already been found. Using the > power of call-with-current-continuation, I have constructed an algorithm > that > lacks this deficiency: > >import Control.Monad.Cont > >test f g = flip runCont id . callCC $ \escape -> > do forM_ [1..100] $ \n -> > when (f n /= g n) $ > escape False > return True > > This should perform almost 75% less work in the testFunc1 case! It > certainly > feels much snappier. > > -- Dan > ___ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > -- Mujtaba Ali Alboori ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Math questions
Thank you all you , that is really impressive . I will read your response carefully , and I think this it is enough to understand it. On 25 May 2010 23:43, Daniel Fischer wrote: > On Tuesday 25 May 2010 23:47:30, Mujtaba Boori wrote: > > Hello > > I am try to solve this equation > > > > Define a higher order function that tests whether two functions , both > > defined on integers , coincide for all integers between 1 and 100 > > > > how can I solve this ? > > is there any thing in Haskell library to solve this kind ? > > Sure. Lots of things to do it in different ways. All boil down to > - for each integer from 1 to 100 > - check whether f i == g i > > Look at > > http://www.haskell.org/ghc/docs/6.12.2/html/libraries/base-4.2.0.1/Prelude.html > , there are useful functions for this. You will probably want to use 'and' > or 'all'. > > -- Mujtaba Ali Alboori ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Math questions
Hello I am try to solve this equation Define a higher order function that tests whether two functions , both defined on integers , coincide for all integers between 1 and 100 how can I solve this ? is there any thing in Haskell library to solve this kind ? -- Mujtaba Ali Alboori ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] newbie question how to pass data
Great job Stephen. Thank for explaining . I got it to work. On Tue, Apr 20, 2010 at 9:21 AM, Stephen Tetley wrote: > Hi > > If you are working with characteristic functions (Point -> Bool or > Point -> Colour...) the common way to do this is to manufacture a Num > instance for functions. This gives you syntax overloading of the (+, > -, *) operators. Similarly you might want to overload (or have to > overload) Floating, Fractional... > > Examples using this technique are Jerzy Karczmarczuk's Clastic, Conal > Elliott's Vertigo, Tangible Values, Pan etc. > > To overload Num you have to define Show and Eq instances for functions > as well. Something along the lines of this is adequate: > > type CF = (Double,Double) -> Bool > > instance Show CF where > show _ = "" > > instance Eq CF where > (==) _ _ = error "No Eq on Characteristic functions" > > instance Num CF where > f + g = \pt -> f pt + g pt > -- ... > negate f = \(x,y) -> f (negate x, negate y) > > -- ... rest follows this pattern, Floating, Fractional similar > > If you characteristic function is Point -> Bool then you also need a > Num instance for Bool. > > All that said, I think your formulation of func above is slightly > wrong to fit this style. Its forming a function (-> Point) "to point" > rather than a characteristic function Point -> Bool. > > Best wishes > > Stephen > ___ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > -- Mujtaba Ali Alboori ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] newbie question how to pass data
Thanks Dan. Great help but my problem has not solved yet This doesn't work for type ((Float -> Float)->Bool) to make it easier ignore the rotation and suppose I want just multiplay with whatever (x ,y) and return the result to this type ((Float -> Float)->Bool) note this type is shorten and replace by t Type Point = (Float, Float) Type Bitmap = Point -> Bool so the function type actually func :: Bitmap -> Float -> Bitmap I want to take Bitmap do some calculation on Bitmap the return it as Bitmap. GHCi response for Dan method is this Couldn't match expected type `Bitmap' against inferred type `(a, b)' so it is missing a Bool. hopefully it is clear . On Mon, Apr 19, 2010 at 7:02 PM, Dan Weston wrote: > First of all, your function > > func (x,y) s dg =((x*(cos dg) - y*(sin dg)),(x*(sin dg) - y*(cos dg))) > does NOT work for type (Float -> Float), unless you mean that that is the > type of the unused parameter s. Also, your desired type ((Float -> Float) -> > Bool) itself looks suspicious. It must accept any function (without > something to apply it to) and arbitrarily return True or False. How will you > decide which? I suspect you need another parameter for this function. > > Second, on the off chance you are trying to calculate the position on a > circle scaled then rotated an angle dg from (x,y), that new position is > > f (x,y) s dg = (s*(x*(cos dg) - y*(sin dg)),s*(x*(sin dg) + y*(cos dg))) > > in which case you are missing the s and the last minus sign in your formula > should be a plus sign. > If so, this can be evaluated with greater clarity (and probably accuracy) > in polar coordinates: > > g (x,y) s dg = (r * cos a, r * sin a) > where r = s * sqrt (x^2 + y^2) > a = atan2 y x + dg > > Third, if you did not need the scale, I would use an underscore to make > that clear: > > h (x,y) _ dg = (r * cos a, r * sin a) > where r = sqrt (x^2 + y^2) > a = atan2 y x + dg > > That's all the observations I can make unless you describe the problem more > clearly. Sorry. > > Dan > > Mujtaba Boori wrote: > >> sorry >> ok I am trying to make these calculation >> func (x,y) s dg =((x*(cos dg) - y*(sin dg)),(x*(sin dg) - y*(cos dg))) >> >> This work for type (Float -> Float) >> >> but how can make it work with ((Float -> Float) -> Bool) >> >> because my main function that I want use with. it takes (Float,Float) >> ->Bool) I need to return the same type ((Float,Float) ->Bool) so it could >> be used with other function. >> >> On Mon, Apr 19, 2010 at 5:54 PM, Ozgur Akgun > ozgurak...@gmail.com>> wrote: >> >>Can you at least give an example of how you intend to use this "func"? >>Since you do not describe it's behaviour, it is very hard to make a >>useful >>comment (at least for me) >> >>Best, >> >>On 19 April 2010 16:54, Mujtaba Boori ><mailto:mujtaba.bo...@gmail.com>> wrote: >> > >> > Hello >> > I am sorry for the silly question. >> > >> > I have a function as the following >> > func:: ((Float,Float) ->Bool) -> Float -> ((Float,Float) -> Bool) >> > I am trying to make calculation in this type ((Float,Float) >>->Bool) with Float and then pass the information to ((Float,Float) >>-> Bool) >> > >> > Thank again appreciated. >> > ___ >> > Haskell-Cafe mailing list >> > Haskell-Cafe@haskell.org <mailto:Haskell-Cafe@haskell.org> >> >> > http://www.haskell.org/mailman/listinfo/haskell-cafe >> > >> >> >> >>-- >>Ozgur Akgun >> >> >> >> >> -- >> Mujtaba Ali Alboori >> >> -- Mujtaba Ali Alboori ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] newbie question how to pass data
sorry ok I am trying to make these calculation func (x,y) s dg =((x*(cos dg) - y*(sin dg)),(x*(sin dg) - y*(cos dg))) This work for type (Float -> Float) but how can make it work with ((Float -> Float) -> Bool) because my main function that I want use with. it takes (Float,Float) ->Bool) I need to return the same type ((Float,Float) ->Bool) so it could be used with other function. On Mon, Apr 19, 2010 at 5:54 PM, Ozgur Akgun wrote: > Can you at least give an example of how you intend to use this "func"? > Since you do not describe it's behaviour, it is very hard to make a useful > comment (at least for me) > > Best, > > On 19 April 2010 16:54, Mujtaba Boori wrote: > > > > Hello > > I am sorry for the silly question. > > > > I have a function as the following > > func:: ((Float,Float) ->Bool) -> Float -> ((Float,Float) -> Bool) > > I am trying to make calculation in this type ((Float,Float) ->Bool) with > Float and then pass the information to ((Float,Float) -> Bool) > > > > Thank again appreciated. > > ___ > > Haskell-Cafe mailing list > > Haskell-Cafe@haskell.org > > http://www.haskell.org/mailman/listinfo/haskell-cafe > > > > > > -- > Ozgur Akgun > -- Mujtaba Ali Alboori ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] newbie question how to pass data
Hello I am sorry for the silly question. I have a function as the following func:: ((Float,Float) ->Bool) -> Float -> ((Float,Float) -> Bool) I am trying to make calculation in this type ((Float,Float) ->Bool) with Float and then pass the information to ((Float,Float) -> Bool) Thank again appreciated. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: help with Haskell programming
Thanks a lot guys you were really helpful func f1 f2 x = (f1 x) || (f2 x) is working for me On Sun, Apr 18, 2010 at 6:27 PM, Thomas Davie wrote: > To do this, you need not just fmap (composition), but also ap, or the > combined form, liftA2: > > func = liftA2 (||) > > Bob > > On 18 Apr 2010, at 18:21, Keith Sheppard wrote: > > > Using composition can be tricky with more than one arg. I just want to > > be sure you're not really looking for something like: > > > >> func :: (a -> Bool) -> (b -> Bool) -> (a -> b -> Bool) > > > > keeping with your given type I think you're looking for something like: > > > >> func f1 f2 x = (f1 x) || (f2 x) > > > > I'm sure there is a nice way to do this with function composition but > > I still find composition less intuitive than explicit args in cases > > like this. > > > > On Sun, Apr 18, 2010 at 1:00 PM, Mujtaba Boori > wrote: > >> Thanks for helping me but I have another problem (sorry for asking) . I > >> tried to figure it out . > >> how about if I want to compare two kind with (&&) (||) for > >> func :: (a -> Bool) -> (a -> Bool) -> (a -> Bool) > >> > >> I tried some thing like > >> func = ((||) .) > >> This is the annoying part about Haskell . I can not understand > composition . > >> > >> On Sun, Apr 18, 2010 at 4:35 PM, Mujtaba Boori > > >> wrote: > >>> > >>> Hello I am kinda newbie in Haskell you can help help me with some > >>> programming > >>> I am trying to make function like for example > >>> func :: (a -> Bool) -> (a -> Bool) > >>> this function make calculation and return bool . I want to be able to > >>> make bool True when It is False and False when it is True while > returning > >>> the a. > >>> Thank you > >>> -- > >>> Mujtaba Ali Alboori > >> > >> > >> > >> -- > >> Mujtaba Ali Alboori > >> > >> ___ > >> Haskell-Cafe mailing list > >> Haskell-Cafe@haskell.org > >> http://www.haskell.org/mailman/listinfo/haskell-cafe > >> > >> > > > > > > > > -- > > keithsheppard.name > > ___ > > Haskell-Cafe mailing list > > Haskell-Cafe@haskell.org > > http://www.haskell.org/mailman/listinfo/haskell-cafe > > -- Mujtaba Ali Alboori ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: help with Haskell programming
Thanks for helping me but I have another problem (sorry for asking) . I tried to figure it out . how about if I want to compare two kind with (&&) (||) for func :: (a -> Bool) -> (a -> Bool) -> (a -> Bool) I tried some thing like func = ((||) .) This is the annoying part about Haskell . I can not understand composition . On Sun, Apr 18, 2010 at 4:35 PM, Mujtaba Boori wrote: > Hello I am kinda newbie in Haskell you can help help me with some > programming > > I am trying to make function like for example > > func :: (a -> Bool) -> (a -> Bool) > > this function make calculation and return bool . I want to be able to make > bool True when It is False and False when it is True while returning the a. > > Thank you > > -- > Mujtaba Ali Alboori > -- Mujtaba Ali Alboori ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] help with Haskell programming
Hello I am kinda newbie in Haskell you can help help me with some programming I am trying to make function like for example func :: (a -> Bool) -> (a -> Bool) this function make calculation and return bool . I want to be able to make bool True when It is False and False when it is True while returning the a. Thank you -- Mujtaba Ali Alboori ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] "Improve Cabal's test support" for Google summer of code
Hello I'm thinking of project for my google proposal . I found "improve Cabal's test support' is really interesting .I have a decent knowledge about Haskell programming and testing methods . I was wondering if this project is suitable for me and what skill I required to have. I would be very thankful if you give me advice for resources to look and understand it. Thank you -- Mujtaba Ali Alboori ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Google summer of code idea.
Hello I would like to discuss my idea for google summer of code. I'm an active Haskell programmer . I have read the idea list . I think Improve Cabal's test support really suit my ability of haskell. I would like to give me advice about my idea . and how to improve my proposal . Thank you. -- Mujtaba Ali Alboori ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
