# [Haskell-cafe] newbie question how to pass data

Dan Weston westondan at imageworks.com
Mon Apr 19 14:02:38 EDT 2010

```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)))

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 <ozgurakgun at gmail.com
> <mailto:ozgurakgun at 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 <mujtaba.boori at gmail.com
>     <mailto:mujtaba.boori at 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.
>      > _______________________________________________
>      >
>
>
>
>     --
>     Ozgur Akgun
>
>
>
>
> --
> Mujtaba Ali Alboori
>

```