Mapping list with function in Haskell

Question

I am new to Haskell and I'm trying to change the position of a drawn path.

let redPath =  Path[Point 420 750, Point 420 550] red Solid

drawPicture 10 [redPath, movePictureObject (Vector 100 100)
redPath]

The functions movePictureObject and movePoint should change every point of the path with a given vector (100,100).

movePoint :: Point -> Vector -> Point
movePoint (Point x y) (Vector xv yv)
  = Point (x + xv) (y + yv)

movePictureObject :: Vector -> PictureObject ->PictureObject
movePictureObject vec (Path points colour lineStyle) 
  = Path map (movePoint (points vec)) red Solid

I am not sure of how to use the map function properly, I have read several posts here and watched other tutorials.

Thank you.

What is Path? What is Point? What is a PictureObject? What is Vector? Why is this tagged dictionary? And what is your actual question? — Zeta
– Zeta, Commented Mar 14, 2017 at 7:05

arrowd · Accepted Answer · 2017-03-14 07:10:10Z

1

My crystal ball tells me, that you just need (map movePoint (points vec)) instead of map (movePoint (points vec)) in the last line.

answered Mar 14, 2017 at 7:10

arrowd

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2 Comments

Daniel Wagner Over a year ago

(map (\p -> movePoint p vec) points) seems more likely to me.

torjussa Over a year ago

That did it @Daniel Wagner

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