C:\Users\mayton\Documents\Haskell>tut02.exe
eee
Enter you name : Hello eee

Enter you name :
sss
Hello sss

import System.IO
import Text.Printf

tostring :: Vector -> String
tostring (x, y, z) = 
 "(" ++ x ++ "," ++ y ++ "," ++ z ")"

v1 = (3.0, 4.0, 5.0)

main = do
  putStrLn ( "v1=" ++ (tostring v1) )

.....
card.hs:43:33: error:
    * Couldn't match expected type `[Char] -> [Char]'
                  with actual type `Double'
    * The function `z' is applied to one argument,
      but its type `Double' has none
      In the second argument of `(++)', namely `z ")"'
      In the second argument of `(++)', namely `"," ++ z ")"'
   |
43 |  "(" ++ x ++ "," ++ y ++ "," ++ z ")"
   |                                 ^^^^^
Failed, no modules loaded.

int tracer(Vector o, Vector d, double &t, Vector& n) {
   .....
}

tracer :: Vector ->  Vector -> (Int, Double, Vector)

newtype Vector = Double Double Double deriving (Show,Eq)

Prelude> :l card.hs
[1 of 1] Compiling Main             ( card.hs, interpreted )

card.hs:27:18: error:
    * The constructor of a newtype must have exactly one field
        but `Double' has two
    * In the definition of data constructor `Double'
      In the newtype declaration for `Vector'
   |
27 | newtype Vector = Double Double Double deriving (Show,Eq)
   |                  ^^^^^^^^^^^^^^^^^^^^