data Tester = Tester [Example] deriving(Eq, Show)
data Example = Example Property deriving(Eq, Show)
type Property = Integer
exampleOne = Example 1
exampleTwo = Example 2
theTester = Tester [exampleOne, exampleTwo]

changeValue (Tester [Example value]) newValue = Tester [Example newValue]
changeValue (Tester ((Example value):xs)) newValue = Tester [Example newValue] ++ changeValue (Tester xs)