Example
Types instantiating Ord include, e.g., Int, String, and [a] (for types a where there's an Ord a instance). If a type instantiates Ord it means that we know a “natural” ordering of values of that type. Note, there are often many possible choices of the “natural” ordering of a type and Ord forces us to favor one.
Ord provides the standard (<=), (<), (>), (>=) operators but interestingly defines them all using a custom algebraic data type
data Ordering = LT | EQ | GT
compare :: Ord a => a -> a -> Ordering
Required methods
compare :: Ord a => a -> a -> Orderingor(<=) :: Ord a => a -> a -> Boolean(the standard’s defaultcomparemethod uses(<=)in its implementation)
Defines
compare :: Ord a => a -> a -> Ordering(<=) :: Ord a => a -> a -> Boolean(<) :: Ord a => a -> a -> Boolean(>=) :: Ord a => a -> a -> Boolean(>) :: Ord a => a -> a -> Booleanmin :: Ord a => a -> a -> amax :: Ord a => a -> a -> a
