Overloading

• Numeric operations are similarly overloaded

• The type of + is

           (Num a) =>  a -> a -> a

• So you can add two Integer arguments and get another Integer

• Add two Float arguments and get another Float

• Define your own Vector type

• Declare that it's an instance of Num

• Define + (and *, etc.) operations on it

• And then add two Vector arguments and get another Vector

• But if you mess up and add a Vector to an Integer you'll get a compile-time error

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Copyright © 1999,2008 Mark Dominus