[Haskell-beginners] instance 2

hi, data StringOrInt = TisanInt Int | TisAString String instance Eq (StringOrInt) where  (==) (TisanInt v) (TisanInt v') = v == v' (==) (TisAString s) (TisAString s') = s == s' prelude> Instance_testen.hs:4:37: error:     Ambiguous occurrence ‘==’     It could refer to either ‘Prelude.==’,                              imported from ‘Prelude’ at Instance_testen.hs:1:1                              (and originally defined in ‘GHC.Classes’)                           or ‘Main.==’, defined at Instance_testen.hs:4:1   | 4 | (==) (TisanInt v) (TisanInt v') = v == v'   |                                     ^^ Instance_testen.hs:5:41: error:     Ambiguous occurrence ‘==’     It could refer to either ‘Prelude.==’,                              imported from ‘Prelude’ at Instance_testen.hs:1:1                              (and originally defined in ‘GHC.Classes’)                           or ‘Main.==’, defined at Instance_testen.hs:4:1   | 5 | (==) (TisAString s) (TisAString s') = s == s'    |                                         ^^ [1 of 1] Compiling Main             ( Instance_testen.hs, interpreted ) Failed, no modules loaded. what gives?