Instances of type classes

• Types explicitly declared as members of particular type classes

  • Use instance construct
  • They must provide implementations of the type class’ operations

instance Eq Int where

x == y = intEq x y

x /= y = intNeq x y

instance Eq Float where

x == y = floatEq x y

x /= y = floatNeq x y

3 == 4 -–allowed

3.4 /= 5.6 --allowed

3 == 4.5 --type error

“hi” == “there” –-type error

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