Re: [Haskell-cafe] newbie question how to pass data

20 Apr 2010

      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 > 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.boori@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.
    > _______________________________________________
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    > 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